#1....safety harness on. After that it doesn't matter if your 15 feet or 50 feet up a tree and that's coming from someone who fell 30 feet and spent several hours dragging himself out of the woods. You climb as high as you need to take advantage of the area you're hunting. Sometimes you need to be 50 feet up and I've been there several times already this year. I had to add more pull rope at 2 of my stand sites already. Depending on what type of tree you're climbing you could possibly be more visible at farther distances to the deer. I also believe that it certainly helps to place your scent stream over the deer's nose particularly at closer ranges. Extra height also may help you see down into thickets or grass fields. One of my climbing trees is in a hollow 12 feet below ground level outside that hollow. I have to get 50 feet up to be 38 feet high. It does make for a sharper trajectory at close ranges but as long as you take that into consideration before the shot there should be no problem.

After all that my typical height is 18-25 feet but like I said, you do what you need to do in any given situation. On the other end of the spectrum I have climbed some trees that were smaller than many I've found rubs on. As far as height phobias, it's all mind over matter. There is no difference in 10, 20, 30 or 50 feet.