For more rivers check the original thread, the next updates will probably be just, truck loads, of rivers and rivers related problems.
Honestly i just go with my guts and put things here i think it will look good, but a good general rule is, in major mountain ranges, since this ones still are subject of tectonic activity, one side should be low and flat and the other should be ruged and elevated, but most of it is just instinct and looks.
The climate related stuf probablia aldo and up in the original thread, and most important, the making processes.