I personally do not hunt pronghorn with a bow, but I have talked to many who do on the ranch where I hunt.  Depending on the amount of water available, and this year we have plenty on the ranch, setting up a ground blind near a water hole does prove successful.  Another option though is to find a well used fence crossing and set up over looking that.  Pronghorns have a tendency to hang around them waiting for the herd to cross the fence if they are not spooked.  Once most of them have crossed, they will begin to wander off in their intended direction. 

Water holes are a good place, but don't limit yourself to them.  A well used fence crossing can be just as productive.

Our group hunt antelope alot with bows and we hunt water hole 80% of them time, the other would be spot and spook or like said before fence line is a good place to get after them also.

The water hole seems to be the easiest because you can be in a blind and will have no problem moving with out being seen.  Drawing the bow back on an antelope in the open is the toughest part.

I prefer spot and stalk. It is a real challenge using the little bit of topography that you have to get up close to them.