I don't have much in my mind to help you now, but i think that's more of a thing you learn by practice, would you mind saying how far are you in the game, what game are you playing and which character ?
This will give me some info to work with, but for now, i have this small tip:
Don't worry in aiming the shots if you are having trouble dodging, just focus and dodge, if you feel like you can't keep up with the attacks, bomb then, it isn't worth risking a life trying to avoid something that will probably kill you.
Hope this helps.