Paul's comments don't really get into the depth that the subject can go and neither will mine (sorry).

But one thing I might disagree with Paul about - and that is that sometimes the vertical location of the horizontal seems to be tied to the intended use of the airplane - think about the type of airplane you are considering and do some lookup and research on the net. It is interesting for example that the really big full scale heavy lifters have T tails. The people haulers have more conventional tails. Aerobatic RC non-scale ships line up everything (at least the new ones, the older ones had high tails and low wings). Older power free flight contest models have wing on pylon and low tail. Full scale aerobatic ships tend to have low wings, some mid wings and tails everywhere except on the bottom of the fuselage and the top of the rudder - And so it goes.

The thing is also that for every 4 examples you can find there will be an exception which keeps it really interesting.