RE: How to avoid "spin outs"?
OK, smaller freeride-freestyle type boards with small curvy loose fins.
On these smaller boards, you normally use very small (20-30 cm) fins that have a very curvy outline profile and and very twisty "tip".
They turn really easily, and are made to be very "loose" so you can do the tricks (on the freestyle boards) or slash and off the lip on wave type boards.
So, they seem to "spin out" very easily with these tiny fins.
If you get a more slalom oriented (more vertical and straighter planform) fin for your board, you won't get s much spin out, and your board will be more directional and easier to sail in the "back and forth" mode.
You also will get much better upwind performance and better speed as well.
Hope this helps,