Like Matt said practice, practice. And remember practice doesn't make perfect neccessarily. Perfect practice does make perfect performance though.
I am lucky in that I've got a setup with two taxiways about 500' apart. I make it usual practice to land and depart between them in the dirt whenever possible. Not usually at gross (3700' field elevation) but full fuel and two guys and a bit of gear. It's uphill east and downhill west. I am fairly proficient at it. When I'm heavier I usually start with 10' of flap and stroke in full when I get to the other taxiway. I like that method when you want to break ground but can accelerate in ground effect. It isn't so critical that I'd wreck the airplane if I over ran it but it would get pretty bouncy. This allows me to know fairly precisely what my capabilities are with my airplane and because I do it all the time I feel comfortable with it.
The best thing you can do when practicing is to be really specific about where you want to land do it until you get the sight picture and then do it five more times in rapid succession.
I like the MAF rule of 700' at gross. I don't think I could do that at 3700' but I bet I could do 900' or so.