Oh I do love sparring!
Sparring is a learning experience, it's your chance to put what you learned in the context of a particular form to practice. Now some things work for some people but not for all. Me, when I spar I decide ahead of time which particular form or animal set I'll incorporate in my strategy, in order to discover the practical applications. This opens me up for receiving hits at times while I'm learning how best to use this particular form, but at least it's in a friendly environment where nothings really at stake except my pride. And since, this is a learning experience, you can ask your sparring partner to slow down a bit while you figure things out. I know this doesn't sound very appealing or macho, but I feel its vital as a learning tool so that what you learn in forms can be used in combat. I've seen too many matches where the two squaring off are upper belt levels that have a lot of different techniques under their belt, but they stick to sparring techniques, or (sometimes...maybe) short forms. What's the point of learning these forms if you're not going to use them? Also, sparring is not fighting, you can't do certain things in sparring that you can do in a real street fight. Your sifu will frown on you breaking your partner's kneecap, but in a real fight that's one of the first targets I go for. Anyway, the bottom line is there is a progression of development in your study of martial arts:
1. learn the form
2. experiment different techniques while sparring (learn first hand their practicality)
3. pick and choose the techniques you like and use in sparring
4. continue to experiment; try to use less favorable techniques to understand them better
5. incorporate more that you learned from past sparring techniques, until you have a wide range you can pick and choose on the fly while sparring.
Repeat this cycle until you have experimented with all that you've learned, the reason why black belts seem so good is because this is how we learn and strive to get better. Remember, when a black belt challenges you in a sparring match, don't look at it as a test or something personal. They're simply interested in how you progress, and if you implement this form of learning in your sparring, then they'll show an interest and even give you the tips and tricks that you're looking for.
Happy sparring!