I don't mind playing anyone. PSN = Compbros. As for advice.
For pressure F23 breath is without a doubt your best tool but don't abuse it because, despite what people say, it CAN be blown up. Instead of going just F23 breath again and again use it to get advantage for other things: Backdashing to negate any punish attempt and punish them if possible ; air dash (instant if you can manage it) to catch backdashes, open up people blocking low/crossup or to punish people attempting to poke out; etc...
For mixups Supes is iffy because he has a really punishable low scoop and a very slow overhead string. Throw either of these out sparingly and use scoop mostly with your 22 string as 223 is overhead and it puts them at 50/50. F2D1 is a nice string for a low on the second hit and you can use breath to make it safe or hit confirm for 30~ percent.
The combo stuff is just practice.
And
Chongo is wrong, I am the "self-proclaimed Best Superman in the World!!!!!!!".