First settle your hand into your usual grip on the bow. Then nock the arrow, taking care to get it at exactly right angles to the string. The eye is a very good judge of right angles. The, if you think that you need to, move the arrow nock up 1/8 inch or so.
I agree with Pat about bow length. The longer the bow, the steadier it is to shoot. My bows are usually 75 to 78 inches. Anything longer is too clumsy to take round the woods.