What tricks have you learned that have really improved your yoyoing skills, and why?
For me, the matrix helped me master reverse flips and and encouraged me to throw them in more combos. Also skin the gerbil and cold fusion really helped me perform combos more smoothly without losing spin or messing up.
What about you guys?
since i am not very far into learning the tricks, i would have to say all of them are making me a better player. a lot of them build on each other. believe it or not the sleeper is a trick. you really could not go far without that one. then the trapeze and double or nothing to help aim and align the yo-yo to the string horizontally. the ladder is challenging me at this time; helps to develope aligning the yoyo to the string vertically. each trick add a new element to the base skill and it is always fun and satisfying once things start coming together and smoothing out. good luck and interested to see what others have to say.
gw
Skin the Gerbil was a major one for me. Helped me kinda grasp horizontal as well 
Bomb of the Spirit variety