Slice through the water on your side
Be a sleek yacht, not a barge
Appreciate the most athletic position, the most powerful position, with the most stored energy and the least resistance, in freestyle and backstroke, is on your side, hips vertical or a little past vertical.
Your default position, the position you always return to, is on your side, hips vertical or one click past vertical.
When you are level in the water you swim with your arms and legs. When you are on your side you engage your core — the largest, strongest muscles in your body.
So use them