What uppercut attacks are you referring to? Mishima electrics? There is plenty of tutorials on how to do them just search "EWGF tutorial" on Youtube. As for the other potential uppercuts you might be referring to, while standing moves come to mind. While standing moves need to be inputted as you are ducking, then letting the directionals go to neutral, then immediately hit your chosen while standing attack. Most characters have a while standing 2 or 1 that's an uppercut launcher that are generally unsafe on block, anywhere from -12 to -18. While standing 4 is generally the go-to punisher for most quick lows that don't do much damage and don't knock down.
Most bread and butter combos can be done without dashing forward. You only need to dash forward after you have used your tailspin/screw attack or when you get a wallsplat. The 1st hit of the combo after the launcher generally needs to do a lot of damage due to how scaling works. To help you time your combos better, use the hit analys/hit detection/hit recovery indicator function in practice mode so you can see the exact moment a move recovers.