Tips

First historically black belts and belt rankings are a recent invention as far as martial arts are concerned. The inventor is thought to be Kano Jigoro the founder of judo and the first to use a belt system in the 1880s. (many other styles didn't adopt belts till 1920s-1950s for Japan and Korea) originally their was only a black and a white belt (obi/sash at that time) colored belts were added in the 1930s, belts makes sense in a style like judo that is a competitive sport, because a belt allows you to easily match up people with similar rank in inter school competitions. Also the number of students at some of these schools are huge, at the kodokan (judo) they have thousands of students that come their to train. So a visual reference like a colored belt would work well so students and teachers can tell who is who. But traditionally martial arts was learned to help you defend yourself or to better your health often learned from a family or village system. In the same way the son of a blacksmith would learn his trade from his father he wouldn't receive any sort of ranking he would just train till he was proficient which would often take many years.
  Now in present times what does it mean if someone says they have a black belt? Unfortunately nothing if you don't know the school it came from, because their is no accepted standard for what being a black belt entails. Their are some schools where it might take ten or more years to achieve a black belt with rigorous testing. But there are other teachers even well known ones that if you pay them a set fee (and maybe take a seminar or two) they will make you a black belt, you can also get them from some schools by doing online courses and of course people can lie and say they're a black belt when they aren't (it's easy to download templates to print out black belt certificates and any martial arts store sells belts). The average time for most schools is about two to four years (though I've heard as little as 4 monthes from legit schools if you go every day). Belts are also used both as a motivator and as an extra way to make money for many schools by charging for each test and charging at higher rates the further you advance. Another thing some schools do is have students sign a black belt contract that locks them into paying tuition for a set number of years, some of these schools will pass anyone that shows up and pays their tuition. Also a black belt isn't an end, most schools that do use belts have ten degrees you can advance after getting your black belt, with the student not considered a teacher till reaching second or third degree black belt in many of them, (again no standardization) and the tenth degree is often reserved for the founder or highest ranked member of the style. Which is why a tenth degree black belt can mean less then a first degree (any of you reading this can create your own style and give yourself a tenth degree black belt as founder of the style).
  Particularly when you go outside of Japanese and Korean styles (the ones that use belts the most) you'll see most martial artists don't use belts at all or use completely different colors if they do. Styles that don't use belts can include (though some of these are adding them also) sport styles like MMA, boxing, kickboxing, combative systems like those used by soldiers, and police, styles practiced more for health like Tai Chi, styles that are trying to train in a traditional manner (remember any kung fu style such as shaolin, wing chun, bagua, or styles such as kali, penjak silat etc. don't traditionally use belts, though many in the U.S.A. and Western Europe are adding them in an attempt to compete with schools that do use them).
 Having said all that there is nothing wrong with using belts (I've considered adding them for kids classes myself) they have good and bad points. On the good side it can help in setting goals and motivating students, especially younger ones(my son's school even uses the black belt ranking system in their music class). On the other hand traditionally many masters would teach each student differently depending on their strengths and needs, but a belt system creates a standardized system of curriculum which just like in public schools this can bring up the quality of the worst teachers because it tells them what to teach but it can stifle creativity in both students and teachers of the best. Another problem with belts is it often causes the student and teacher to focus on moving on to the next level as fast as possible because the student wants that black belt but the most important thing in martial arts (and most things) isn't learning more advanced material but really perfecting the fundamentals (which even instructors should continue to work on). A common question people ask you when your a martial artist is are you a black belt? Unless you know the requirments of the system someones trained in, a better question would be how long have you been training? because that question would not be style specific. If someone does say they're a black belt again this on average would mean they've been studying about three years (for first degree) which for most people would still be a beginner or at most an intermediate level martial artist if they practiced really hard, unless the teacher or student (or better yet both) is really exceptional then they might be at an advanced level.

Be adaptable and don’t get locked into combinations because you can’t predict what your opponent is going to do. Always prepare for different possibilities. For example practice what you would do if in the middle of your combination they threw an attack, blocked what you were doing or stepped out of range. Once you can do the technique with your partner just standing there then have your partner try these or other variations. If need be stop and analyze what you should do and then practice it. Continue to do this trying as many possibilities as you can this way you become better prepared for anything that can happen.

Controlling Distance
One of the many reasons footwork is important, is to control distance. In general, each type of fighting has its preferred range. Whether you're a grappler, boxer or kicker (close, middle and long range) you want to fight from your preferred range and not your opponents. For example, take a grappler who primarily works his ground fighting but neglects his footwork and entries. If he fights a boxer with better footwork, each time he tries to enter, the boxer will step back maintaining a middle range and hitting the whole time. This will ensure the fight never goes to the ground. On the other hand, if a boxer or kicker practices mostly strikes from a stationary position in front of a heavy bag or focus mitts, they will likely stand stationary during a fight. At this point if a grappler tries to enter on him, the boxer will throw strikes standing still. This means he will usually get only one strike off before he's in grappling range and possibly taken to the ground. Now if you add weapons, controlling distance becomes even more important and will be heavily dependent on your footwork. It's best not to neglect your footwork in favor of fancy techniques. Without good footwork you will have a hard time getting in position to use those techniques.

Judging Distance
It's very important to judge distance. Many schools teach their students to throw strikes with full extension that end a few inches from their partner for safety. The problem with this is the attacker learns to attack outside of range and the defender defends strikes that would never hit them. How I prefer to teach is to have the students go slow enough and use control to pull their strike a few inches short while being in range (not fully extending the strike). When sparring (this way) or fighting, if someone throws a strike fully extended out of range rather than just trying to be safe you know they are doing it for one of three reasons.

• They misjudged distance in which case you can take advantage by counterattacking.
• They’re trying to see your reactions (how you will block, evade or counter) to know how to best attack you next.
• The attacker is trying to pull you out of position with a false attack getting you to open your guard by chasing an attack that isn’t real then stepping in with the real attack.

So it's best if you don't block any of these, as you are not in real danger until the attacker moves into range this way you maintain your guard and don't give your opponent any information. It is equally important for the attacker to know their range with all of their strikes and to use the appropriate strike for the range they are in and to not attack out of range as this can create an opening especially with weapons as an attack out of range might bring your attacking arm into range for a counterattack.

Shadowboxing (see video on same subject for more info and demo)is just practicing your techniques in the air. You can do prearranged patterns or improvise your own. When you start out its best to do simple combinations that you've been taught (to make sure the combinations work together) but as you advance its best to start making up your own combinations and variations. At this point you will be improvising which is important to feel comfortable doing because if you ever do have to defend yourself real fights require you to improvise because like having a conversation with someone you can't plan out ahead everything that will be said because you don't know what the person your talking to is going to say, the same is true in a fight you need to constantly adapt to what your opponent is doing. When you do shadowbox it should be done at all levels of speed, power and exertion. For instance, if your max speed is throwing four strikes in a second, then most of your shadowboxing should be spent throwing one or two strikes a second. This way you can work on your combinations, balance, body mechanics, relaxation etc, to really perfect your technique. Only doing the three per second when you can do them perfectly and relaxed (if your making mistakes your going to fast) and only rarely doing the four per second. If you want to develop speed what will make you faster is good body mechanics, relaxation, clearing your mind and repetition. The risks of doing your max speed too much is greater chance of injury (pulled muscles, hyper extended joints.) Also at max speed it's easy to get sloppy and you will tire out quicker, not allowing as many repetitions (the repetitions is what you need to get faster). Learn to use all of your techniques. Don’t limit yourself to boxing techniques (unless you’re a boxer.) Shadowboxing should include strikes, joint locks, throws, sweeps, defensive actions, and footwork, everything in your style. At first you might visualize an opponent most of the time to make sure your combinations make sense, at other times you can work on not thinking and just clearing your mind and allowing techniques to flow this is more the mindset you want when actually fighting or sparring (this creates a form of moving meditation the same as practiced by shaolin monks)