The best thing you can do is NOT post up in the paint, first off you are leaving yourself open for a very quick 3 second call and thus a turnover. And also the AI never reacts quickly enough to pass it to you.
What i do when playing PF/C is post up next to the paint closer to the baseline or near the elbow of the paint. And after getting the ball i will quickly try to back down close to the basket and try to go for a post shot or hook (depending on what i am skilled at).
Another good tactic is to try to roll past your man and then go for a dunk/layup, if you manage to pass your man the other big man needs to close you out which means you can get fouled or get your team mate open for a open shot.
Another thing that has been made very strong is the Nowitzki-style post&fade if you make it good/great you will start to put up huge numbers with relative low chance of getting blocked. (it still happens)
But i personally never start posting up inside the paint because it doesn't really give you a significant edge over posting up next to the paint.
Also try to avoid to muscle your way into the pain with RT/L2 because you can easily bump your opponent onto the ground and that will get called as a charge and a foul+turnover. Just go easy and try to get as close as possible, if you get stopped maybe give one bump before going for the net and that's all. If your post up skills are high enough and also your strength is up there (80/85+) you can easily back the average Center/Power Forward down.