The best way of getting "realistic" topography is by using real topography. In a world I recently began creating I was sure that the adventurers were going to scrap the quest at some point and build a castle in the mountains. Since I needed a highly detailed realistic map that would be usable I simply found a map of an island of roughly the same latitude. Since that map had plenty of information about the land I was able to give very good descriptions with very little work, unfortunatly it was not a creation of my own and that came with some shame (
) but I think that strategy works on a small scale. I hope you find this useful!
-If you haven't already, it's a good idea to draw out a rough description of the techtonic plates of your world, by doing this you might even be able to figure out where major deserts are going to be.
-Coastlines look drastically different at different lattitudes
-A coastline riddled with fjords can be drawn by making a river system and then expanding the width of the rivers until they look like fjords
-Coastlines along large deaserts are usually pretty smooth
-when drawing rivers, tributaries usually enter at right angles to the actual main stem of the river
-Older rivers and ones that run allong flat topography tend to wind a lot, there are some in Africa which almost double back on themselves.
(if you figure out a good way to determine ocean currents please share