You'll learn through experience. Learn to shoot sitting. For 8 or 9 years, hunted standing up in my stand 100% of the time, you're always ready. Go higher with your stand, 17'-22'. Don't hunt in the same stand, keep moving it. Lastly, I've known guys who put stands in areas with no cover around, they're just in the open. I've known guys who hunt in such thick cover they might only have one or two 1' shooting lanes and can't even see the deer until its in that exact spot. Both of these situations are bad. You need a mix. If you have enough natural cover and are high enough, you can move around in the stand a fair amount.

Good Luck!

PRACTICE....PRACTICE....PRACTICE......SUCCESS!