Not to belittle you, but have you ever used a joystick before? I ask because if you have trouble with using a stick, the problem could just be as simple as getting accustomed to reacting as fast to convex buttons as you do with joypad buttons. Again, no offense, it’s just to make sure. Anyhoot, if you haven’t, it’ll probably just take time, and you should do well to practice as much as possible using a stick to get more precise execution of moves. This will become important when you start wanting to learn advanced tactics for Urien (charge partitioning, advanced unblockables, etc.).
If you already use a joystick a lot (like, say you’re a GGXX/MvC2/CvS2 player), then the problem could probably just be 3s timing difference. While more lenient than the other games in terms of how long you have to make two attacks combo, it’s still enough to throw you off. Again, the suggestion is the same, but for a different reason: keep practicing on the stick to get the timing down 'cause it’ll only come with practice.
As for parry practice, since you’re just getting started with 3s, i think the best advice is to at first not think about it so much. If you can parry a fireball that’s thrown from far away, that’s good enough. Don’t overestimate the power of a parry, which, while a pretty good momentum changing maneuver, can also get you into trouble (e.g., if you become a parry whore without working on tech throwing, the opponent will just throw you around like a rag doll while mixing in combos when you don’t expect 'em). The harder parrying will come over time, as you get used to your own character’s moves, and the moves of other characters, simply from recognizing them over time. Parrying isn’t always all it’s cracked up to be
Hope that helps