This is the very abridged version of how I gameplan.
I always look at individual matchups when playing against a man to man defense, and adjust distro accordingly. For instance, if i have a stud SF with 70 ATH and 90 LP, and he will be guarded by a guy with 40 ATH and 30 DEF, that stud SF is getting more distro. Distro is a huge part of gameplanning.
Against zones, I look at whether I expect the opponent to play a 2-3 or a 3-2, and adjust accordingly. Against FCP, I make sure i've got some decent ballhandlers and passers playing minutes in the backcourt, and then I will do more penetrating and pounding the ball inside, hoping to draw more fouls (Press teams commit more fouls, so I'm always trying to find a way to get some of their key players into foul trouble)
Positioning on defense is important as well, but don't rely too heavily on it. My positioning decisions are usually based on the opposing team's ability to rebound, as well as their desire to shoot 3 Pointers vs. 2 pointers. A lot more goes into it than that, but it's a start.
It's important to look at the opponent's previous games played for any tendencies. Maybe the opponent played every game at a 3-2 zone with a +3......if that was the case, I would pound the ball inside a little more.
Regarding uptempo/slowdown, I like to run uptempo with my team if my team has more depth, or if my team has more ATH/SPD and will get to the FT line more often. I like to run slowdown when I have less talent, or a deliberate, skilled passing team in which the starters are much stronger players than the reserves. I run normal if I just can't make up my mind.
Glad to see you are interested in getting better. It's an addicting game! Take everyone's advice, but develop your own style......you'll also get better with lots of trial and error.