Regardless of whether you do open turns or flip turns you come off the wall on your side (If you don’t you need to ask a coach to fix your turn). As swimmers push off many want to take their first pull with their dominant arm. This is very natural and perfectly acceptable if your dominant arm shoulder is closest to the bottom. If you are doing a flip turn you are free to roll in either direction, so if you want to pull your first stroke with your left arm roll counter clock wise, this puts your left arm and shoulder below you (closest to the bottom). To pull with your right roll clock wise. Many mistake pulling with the bottom arm with the bottom hand. It is not which hand you place on top, but which way you rolled your body that determines the arm you should use on the first pull.
If you do open turns you will take your first pull with the hand opposite the one you used to touch the wall (this assumes you are doing an effective one-handed turn). Swimmers often favor their stronger arm and want to touch and pull off both with the same arm.
While it is natural to favor your dominant side, taking your first pull with the arm closest to the bottom provides greater leverage for a stronger first pull.
Start by just noticing which side is down and which side you take your first pull with. If you are pulling with your top arm then you can decide to change the arm you pull with, or change the direction you turn.
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