Lots of practice.

I started last year and rapidly increased in score so I was getting mid to high 80's/100. It took about 9 months of twice weekly practices till I was consistenly getting them in the low 90's. And there are only 8 members (out of 30 or so) who are in the A Team! And only 1 or 2 who get regular 98/100.

My best is 97.

I'm sure there is some muscle memory going on so get someone to check your stance and try to stick to it. Talk to other members about tips.

Also, put the rifle down between shots to relax your arm and if you have been in position too long and you KNOW its wandering then put the gun down, relax and pick it up again. No point in wasting a shot.

Oh, and try and enjoy it. Thats the main thing.