Trick to afterimage is to put it on before you opponent is going to do anything to you, and try to make them think you've used it before you actually have, works really well with kid goku scince the premature teleport is so fast to execute (which is just outiside of opponents punching range while either swooping or standing punch once, then teleport to the side, they'll start comboing in the direction you were while you're standing at the side of them, characters that get off punches fast like kid goku, videl, 3rd form frieza, burter etc, are the best characters to do this with) even then when you're at the side of them start your own combo, if they hit you whilst in a combo afterimage doesnt get used, it saves you from the triangle push/gut punch to throw/beam. By the time you've used the afterimage you've got another ball to use, so you can continuously string it together, never getting hit unless you're in the middle of a combo, with kid goku, nobody will hit you before you've started to hit him, so you're never at risk in melee, as long as you dont fumble, and mix up your hard hits a lot. Afterimage also gets you a free throw everytime somebody tries to hit you =P.