It really depends on the vehicle and how it is set up, but on the loaner vehicle which I felt was terrible, I turned them up 4 turns which was too much. Then I gradually backed it down to about 2 turns if I recall correctly.
So, my advice is to try raising maybe 1.5-2 turns and then adjust 1/2 a turn at a time until you are happy. As other's have mentioned, the driver's and passenger sides are sometimes set differently, so It's nice to have a flat wall about 30' away. Tape a line on the wall or use some other defining point for height, then cover each headlight alternatively with a blanket or something so you can aim them both to the same height.
Again, the key, as I learned, is don't go too high. It's easy to raise the low beams to a point they almost start to function as the high beams, which really is too much because the high beams will actually be shining "out into space" and not illuminating the road at all.