well, I am not good but consider I can usually finish all the combo trainings 100% so my execution is quite okay. (I quit fighting game cause the button tapping is quite noisy, so no more fighting game after my son was born. )

• street fighter have a couple arch type, ryu/ken is shoto and they have actually different play style even though their basics looks similar.
• for any fighting game the distance that your opponent’s attack can reach is very important. a good player can simply whiff punish you and throw jabbing you because you don’t understand the +/- etc after a blocked/whiffed attack.
• hit confirm is also important, which means a simple combo that you can start when you have advantage, but not too “negative” when it’s blocked. (training mode can show these info) Where the first 2~3 hit of your combo is safe and once you get better and landing those 2~3 hit combo, pick something that allows you to cancel into special moves, knock down or throw(which is also a down). All the more fancy complex combo is not really useful if you can’t even land a 2~3 hit combo on opponent.
• punishing specific match up’s bad move, ie. a fireball at wrong distance allows opponent to jump in and lands full combo out of it. you have to do training mode a lot and study your match up.
• and finally, study the neutral game, where both side starts from distance that all normal attacks are out of range, what can you do from that point of space and what opponent’s char can do from their space. If you keep getting beat by opponent’s certain move, rewatch the replay, check their input, record that input to a training dummy, and find what you can do as counter.

It’s a huge time sink and there are also cheaters(on pc specifically), so good luck.