the problem with sf4 is that not only do you have to memorize combos, but you have to memorize the timing of the combos. sort of like parrying in 3rd strike. Also you dont need an arcade stick to become good at sf4. just play with the d pad rather than the stick and it should make it easier for you. Also [] + X lets you grab, this helps a lot if you are being overwhelmed by the enemy (albeit cheap). your focus move, /\ + (), if timed right, can stun an enemy and even gain you back a little health. Its basically a parry, but a more concentrated and charged parry. It's also useful if you're just being bombarded with attacks and have no chance of attacking back.
If you're playing against CPU and want to be cheap as hell, use only the Hard Kick + Punch buttons to fight. Low kicks are cheap too you can get away with dealing a lot of damage just by repetition.
I hope this helps and good luck beating seth!