If you're just starting out you might want to try my method of aiming.
(this assumes shooting a IR50/50 target or similar)
First of all you have to have a very small dot for this method to work. I hold on the rings at the bottom of the bull... not in the center. To me, the "center" is harder to be precise than you think. That's a whole lot of white space (since you can't see the rings) and nothing to confirm that you're actually in the "center". On top of that holding off is even more of a guess. Those assumptions or guesses can easily cost you an X or a 10
If you hold on the bottom you have 5 hold points that can actually be confirmed.
1. Dot touching top of black rings.
2. Dot centered on top of black rings (use cross-hairs with bulls on either side to confirm this.
3. Dot centered in the middle of the black rings.
4. Dot centered on bottom of black rings (use cross-hairs with bulls on either side to confirm this.
5. Dot touching bottom of black rings.
That takes care of vertical holds. You'll find left and right holds also become much easier to consistently visualize.
I mentioned trying this when first starting out as I've found shooters who are used to holding in the center have a hard time adjusting to this method.
Also, don't look through the scope when you pull the trigger. You should have your dot where you want it so what's the advantage of looking through the scope? I shoot heads up so I can watch my flags and pull the trigger when they tell me to. Also, this gives your eye(s) a rest. This becomes very important later in the target (or day).
Always free recoil. the less that you touch your rifle the less things that can change as you shoot.
Good luck! Sporters are the best part of this sport.
Bruce Hornstein