WIP Criticisms welcome!!

[RothgirFellhall]

Hey everyone.

So I'm making a D&D world from scratch, and I'm really in the very beginnings of mapping the world, just trying to get the basic geology down and correct before I flesh out cities/people etc. Below is the bare bones of a continent roughly the size of south america. As this is my first ever map, I expect I have already made some mistakes and don't even know it, so I am asking for some honest brutal criticism, I promise I won't take it badly!!

For reference, the dark green at the top is jungle, the light green is general grassland/hills etc, the muddy green at the bottom is swampland, the brown blip at the top is a salt lake and the grey patch is a highlands type area. Probably goes without saying the temperature is damn hot up north, and gets colder as you go south.
I have also put up the original sketch, it's not a great photo (I dont have a scanner), hence the horribly coloured version for clarity