The World of Caliy [Help Requested]

[SkullCollector]

Hello everyone.

I'm here with my second map done in PS, the first completely copying jezelf's tutorial, and I need quite a bit of help. Not with techniques of actual mapping, but more with the geography. If this, at this stage, would be more appropriate in a different board, I beg for pardon. Please move the thread in that case.

All right, so I've got an amazing theoretical world, planned into every little detail of relevance and even irrelevant stuff.
This one is not it.
I've got a concept, the general and rough stuff like races and so on. A few details about locations, flora and fauna. What I'm basically entirely lacking is geography in all its aspects: political boundaries (which will be up to me, don't worry), mountains, rivers, lakes. These are the things I'm worried about the most.
I tried determining the stuff via tectonic movement, worked well, but I noticed the world would not turn out to be what I liked it to become. So I settled with basic landmasses waiting to be filled with content. While I fancy myself a huge science expert, geography definitely is not amongst my qualities. The basics, sure, that's it.

This is what I have so far:

 

(Zoom level 51%)

Red indicates where I'd place mountains / mountain ranges, blue are cold ocean currents and green warm ones. Note: Very rough and definitely not settled with.
You see, I'd like the southern continent to be warm in the north-east, like England's south coast thanks to the Gulf stream. Never mind the rest of the currents, I just thought I couldn't leave the one alone and made some randomly.
I'm unsure about rivers as well, but those I have I'm happy with.
Islands are lacking a lot, too, I think. I do not deem them necessary so far, though.
Also very important, I guess, is the execution of the map itself. I'm often confused with the placement of stuff along the edges, especially the southern continent here. If you could help me out with a good read about maps, it would be much appreciated.

What I don't want are details for now. It's a Fantasy world for a progressive and dynamic multiplayer story where almost a dozen authors will write their parts with unique characters. Basically an RPG with less constraints, but never mind that.

So yeah, I guess that's it. If you need more information to help, please ask.
Thank you a tonne in advance, I appreciate every bit of advice.

Cheers
SkullCollector