I like it. You seem to have the right idea on planning rivers. Some other areas to look into are Scale, map projections, and climate zones. I know you said the scale is equal to Earth. When you think of global scale: how long are those big mountain ranges which extend across the Equator of your globe? I'm not saying it is wrong, just suggesting you to measure the length of the mountain range on that particular landmass and be aware of how big you're building it, and perhaps compare to the distances covered by mountain ranges on Earth, to see how your idea compares. Also to be aware of where these features and landmasses are located on the bands of climate, from
Arctic
Sub-Arctic
Temperate climate
Sub-Tropical
TROPICAL (crossing the equator area if you want --- lots of your land on 4 continents would probably be in this middle zone)
Sub-Tropical
Temperate South
Sub-Arctic
Arctic / Antarctic

Good luck and please post pictures again with your next map developments.