Learn to hit with things like (d.short, d.jab -> forward hurricane or d.forward -> forward hurricane) -> strong dp on the characters it works on (shotos, twins, a few others).
And yes, you can’t afford to be on the defensive, although attacking all the time isn’t a great idea either. Sometimes it pays off to be tricky by using the demon flip (dp+k), and running away isn’t bad if the alternative is getting put in a corner by a character like Ken or Yun.
His kara-throw is among the best in the game, learn it well. And don’t scoff at the damage from hitting f+strong, throw that in sometimes when they start teching throws. On the arcade version, f+strong is an unthrowable animation, so they will get hit for trying to tech, there is no way for them to throw you for screwing up kara throw.
But don’t play Akuma defensively. If you’re going to play him, keep the pressure on the opponent and don’t let up. He takes horrible damage, and dishes it out with equal harshness, so there’s no reason to turtle, just keep hitting them until they die and you win.