Some trees, tall oaks in my area, taper a lot in a 12 foot climb so you may have to put your stand at a pretty dramatic angle at the base of the tree. It takes a few trys to get it right.

Selecting trees to climb is the tricky part. I made a short rope with some knots tied at several distances. I can put it around a tree and tell if it's to big or small to climb and about where to set cogs on the stands cable.
I like to climb pines best because my stand grabs them real well. But the flakey bark can be kind of noisy. Oaks are ok, if they didn't taper so fast.
Good luck