These are some of the things that worked for me, I'm sure others rely on different methods to help them get better at the game.
1. Badging is super important, I noticed a huge difference in the results after I badged up Pippen and LJ with shooting badges.
2. Learn the player's jumpshot. Timing mistakes are a lot less forgiving in higher leagues. So stick to player jumpshots you're comfortable with.
3. Learn to react and adjust offensively and defensively.
Defensively - I try to read what my opponent is doing offensively in the first few minutes. For example, if they're running a lot of PnR but aren't good at shooting or attacking from the PnR, I'd just go over or under the screen. But if they can run an effective PnR, I'd play off ball during the PnR and bring a third defender to help. Obviously, if you're playing off ball during screens, you'd need to have good defensive settings in your game plan.
When playing on ball, I'd gauge what the other person is doing offensively, if they are good at shooting out of ISO dribbles, I'd stick to them a little tighter, and attempt steals a bit more frequent to force pick up dribble and make them uncomfortable. If they're not good shooters or attacks basket a lot, I'd sag off to defend penetration better, and also know who my help defender is to quickly switch to help. I also refrain from Turbo + Contest jump shot as that leads to a lot of fouls. I'd usually do contest with right stick or the Y or Triangle button, without turbo to minimize fouls.
Offensively, I swear about half of the people I play likes to off ball with their Yao's 80% of the game. I usually pick that up in the first 2 minutes and it's GG for them. I punish off baller's by running Pace motion cut to get good spacing, and call a good amount of with cuts to basket for my center. Off ballers are usually too slow to react to that. I'd also purposely call a lot of PnR or PnF with my center, and they're not very good at defending that manually, it's automatic basket 80% of the time.
You'd also need to be versatile on offense, learn to attack out of freelance, learn post moves, and and money plays to get good looks for your shooters. If you're facing good defenders, you'd need to have many ways to score and always stay one step ahead of your opponents, especially in fastbreak scenarios. There's a lot to learn here, so I'd suggest studying someone like Sam Pham on youtube for that.