Setting up consistent reference points is the foundation for every accurate shot. Remember, great shooting is simply repeating the same thing over and over again. The more and better your reference points, the easier it is to repeat.
If you can't eliminate string contact on your face completely when settling into your anchor point, it's acceptable to have minimal contact. Keep up with the practice and be very cognizent of your references to achieve consistent accuracy and tight arrow groups.
The Peep Sight
Most writers and coaches teach that the most important reference point is your anchor. I do not believe this is true any longer. When we were all shooting without peeps, our anchor point was our rear sight, pure and simple. The advent of the peep made a solid anchor point much less important.
I can vary my anchor point dramatically and still hit what I am aiming at as long as I don't interfere with the string and as long as I'm aiming through the center of the peep.
Obviously, I believe the most important reference point is the peep sight. You would not shoot a rifle without a rear sight and the same holds true with the peep sight on your bow, it is your bow's rear sight. The peep locks in a consistent relationship between your line of sight and the arrow's path.
Peep sights are not without their drawbacks. They reduce visibility in low light conditions and they have a way of creating a mechanical disconnect between you and the target. If you grew up shooting instinctively, you will most likely hate peep sights. However, you can eliminate most of these issues by using a peep with a very large hole. There are models on the market with diameters as large as 5„16-inch.
Anchor Point, Hand Position
The exact position of your release hand against your face is a personal thing. I have friends who place their thumbs behind their necks (a bad idea in my opinion) and others who press a certain knuckle against their ear. Others key off the corner of the jawbone. The anchor point should be repeatable under all conditions including shooting uphill and downhill and it must allow you to shoot your top pin and your bottom pin equally as comfortably.
If you are undecided about the exact place to anchor, I have a suggestion. If you shoot an index-trigger release aid, you will find a very solid, stable and repeatable anchor point by pressing the gap between your thumb and index finger against your jawbone.
This anchor point is very repeatable because you have specific points of contact that you can actually feel even when wearing thin gloves or a facemask. As mentioned, reference points are the key to consistency and if you can't sense them, they don't count. An added bonus to this anchor point is that you can actually open your jaw slightly to shoot your lower pins.
If you are using a thumb-trigger release, invert your hand slightly more than you would with an index-triggered release so your thumb points almost straight down. Press your knuckles into the back of your jawbone.
I would be remiss not to offer a word of caution. When establishing your anchor point, you can develop inconsistencies if you press the string against the side of your face. Rather than try to manage another variable, eliminate it by not allowing the string to contact your face other than at the tip of your nose.
The Tip Of Your Nose
I always touch the tip of my nose to the bowstring. I sometimes even serve a small knot under this contact point to serve as a reference so I know I have my nose in the right place. The tip of my nose is a better reference point than the side of my nose. When contacting just the tip, I am more sensitive to changes in bow angle--giving me necessary feedback to adjust my body to fit the shot.
Suppose you are shooting uphill. If all you do to establish upward angle is lift your bow arm and turn your eyeballs up, you will notice an increase in pressure between the string and the tip of your nose. You can use this feedback to remind you to bend at the waist to align upper body, neck and head in the proper 90-degree angle with your bow arm.
Likewise, when shooting downhill, the string will pull away from your nose if you don't bend at the waist to create the proper downward shot angle.
Some archery hunters try to eliminate their peep sight by using a kisser button. It is definitely another useful reference, but not consistent enough, in my opinion, to permit serious archers to eliminate their peep. If you are touching the tip of your nose to your bowstring, the kisser is nice but unnecessary. However, if you aren't touching the tip of your nose to the string in this way, a kisser is a very good secondary reference point.
Make every effort to consciously monitor and manage your reference points when anchoring and soon they will become automatic and you will shoot more consistently.