Ever went up against a Guile player that has an exceptional ability to pull off a Sonic Boom even when you could have sworn he didn't have enough time to charge it up?
They likely were using a technique called, "charge buffering," that gives you a few extra frames of charge time to execute your moves. Gilley, who's contributed a ton of stuff to the Street Fighter community, put together a pretty sweet video showing the technique in action.
The basic idea is to do the motion for the Sonic Boom, but quickly press back and a Punch button to complete it. Your move should still come out because Capcom's Street Fighter games offer quite a bit of leniency when performing some moves.
In other words — you don't have to do the motion perfectly — and because of this you can re-position your joystick so you're charging up for your next projectile even as the current one is coming out.
Here's how the motion would look if you used Guile's Sonic Boom as an example.
This trick works with all charge characters and it can give you a big advantage in some situations.
#24
it works for any charge type... to master the charge characters this is the next step after learning how to charge...