Take your time picking a holster that suits you. If you know anyone else that carries, see if you can try their rig out.
I personally prefer holsters that have adjustable ride height and cant angle. I have 3 holsters for the same gun, my CZ P07, depending on how I'm carrying.
1 single clip IWB, 1 dual clip, full Kydex holster from Black Rhino Concealment for carrying with my Streamlight TLR-3 attached, and a basic Aliengear hybrid holster.
The Aliengear is the most comfortable. The single clip is the easiest if I know that I'll be taking it on and off a lot. It is a bit harder to conceal. The Black Rhino is the highest quality and most versatile.
Like you, when I started carrying, it was small of back carry, with a M&P 40 full size. After carrying that way for maybe a year, I realized that carrying at around 9:00 (lefty) was much faster and more comfortable for me.
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