On defense be willing to take contact and draw charges for ball control possessions when referees are there to call fouls.
Also have a strong base in your legs and watch the bellybutton of the player your defending at all times. If you stay in front of his or her bellybutton, well no matter the pumpfake or ball fake they cannot move anywhere without their hips. If you watch the ball or their eyes or their legs you can easily be in the wrong position.
Talk to your teammates and let them know where you are guiding your opponent into the baseline, towards a shotblocker, or towards a teammate who can steal the ball from them on a double. Speak verbally to each other with a loud voice: pushing my left, pushing my right, pushing towards you. Or use hand signals to tell teammates behind you what your going to do when they bring the ball to your spot on the court. Towards the shotblockers in the paint, towards the baseline, towards the sideline, towards a double or triple team, or to a angle and place where they cannot pass to a shooter who is hot at that moment of the game.
On offense in the post you need 4 moves.
1) One if your standing still looking at the basket: watch film of duncan’s bankshot off the glass. In general aim for the corner of the white/orange box on the backboard and you will get good bounces towards the rim
2) you need to be able to back in slowly and go to your left or right and you will find most success with a hook shot over your shoulder to the left or the right,
3) a scoop shot/finger roll under their arms or between two defenders coming from a low ball position to evade being blocked.
3) or back in slowly and have a fade away jumper away from your defender
all of these can be done after catching the ball in the post, without dribbling or with maybe one two dribbles and a ball jab to see if your defender is guarding your left or right side.
In your mind and practice time know and believe in patience and mobility instead of relying on overpowering your defender and the 12 players your team is playing against that day. On offense you can move forward past your defender, backward away from your defender and to the left or right of your defender, you can catch and not move or shoot without moving your feet. And you can pass to a teammate. You must always be able to catch, pass, shoot, and dribble(move left, right, backwards, forwards) generally you will use angles forward and angles backward to avoid running over your defender and giving them a ball control possession turnover.
and none of these require high vertical leaping abilities, but if you have that gift than throw it down in their face and go to the free throw line when you get hit and dunk.–