I've heard many a fine priest say that one should celebrate the Holy Mass as if you are alone before God. I have always tried to celebrate in this way and I have the privilige of being at a parish that is ad orientem only.
The only time I celebrate versus populi is when I go to a retirement center where the setting is rather makeshift. I feel the awkwardness because I immediately worry and wonder about how my face should look or how I look when celebrating. This is distracting. When you celebrate ad orientem, the thought never comes to mind. You are simply their to make an oblation and you don't have to look at anyone to do it.
So during this rather small versus populum Mass, I resolved to celebrate most solemnly and pretend that I was by myself.
I made no eye contact except when I address the communicants (e.g. at "The Lord be with you.") And essentially kept my eyes either toward Heaven or directly at the elements on the altar.
Afterward, I got only two comments. The first was, "Oh Father, you celebrate so wonderfully. It was just so beautiful today."
Another elderly lady said, "As you were celebrating it reminded me of Moses and how important it was to take delicate care with sacred things."
I take both comments to reveal that lay people don't want a priest gazing over the altar at them. If you do not or cannot celebrate the Mass ad orientem, simply celebrate as if only God were there. Look to the heavens or to the sacred Sacrament there before you. The priest celebrates with the people and not to the people.