Pretty much all the advice given here thus far is good and should be taken.
I’ve only been playing 3s since about September or October and I still scrub out against AI Gill even though I can own the computer against pretty much every other character. I have more trouble against him with my main (Ken) than I seem to when I play against him using a character I just picked up and I realized that it’s because i play more recklessly with Ken.
DON’T play recklessly. Play a cautious game and don’t take unnecessary risks, at least not yet.
DON’T abuse Urien’s special moves. his normals are some of the best in the game IMO and you could be a beast with him even if you never made much use of his specials.
DO play against other people whenever you can.
DON’T think about it too much. You’ll get there eventually. This game has more of a learning curve than the previous ones did. You’ll get it, just keep practicing.