From a link on crouchers you can go into a fireball or EX, (in the corner you can follow the EX up with a Shoryuken) the fireball can be focus cancelled into a combo, though this will take some practice to get used to. EX Tatsu will also combo from the link for some nice damage.
You can end strings with Fireball, EX Fireball, EX Fireball -> Shoryuken, EX Tatsu, EX Tatsu -> Shoryuken, Fireball FADC string again, tick throw, or cancel a normal into a demonflip for mixup. Many options on crouching opponents.
You can easily hit confirm c.LP, c.LP, c.MP into a much larger combo on a crouching opponent by FADC’ing into st.HK, which stands your opponent up on hit.
c.LP, c.LP, c.MP xx Hadouken, FADC, st.HK, c.LP xx LK Tatsu, HP SRK is a good example, and works anywhere on the stage other than in the corner, and I’m fairly sure on every character. When practicing this combo, be sure you don’t mash HK after the FADC, as most of the time it won’t work. The st.HK must be timed correctly and somewhat precisely in order for it to connect properly. You should be hitting HK the moment the dash animation ends. It’s not as hard to do as it sounds.
In the corner you have other, easier options like c.LP, c.LP, c.MP xx EX Tatsu, HP SRK, or c.LP, c.LP, c.MP xx EX Hado, FP SRK. You can also FADC straight into st.HP xx LK Tatsu, FP SRK if they are in the corner.