Making a map really fast. Need some help, advice and criticism.

[oneman]

Hi guys.

I'm a novel writer and my book is now printing. I'm very short on time(have a bit less then two days left) and need to create a relevant map for my fantasy world. Hopefully i found Cartographers Guild. This place is awesome! I've already found a bunch of tutorials that should help me alot. And usually I wouldnt make a post like this before I got through most of tutorials, but then again, I'm really short on time.
So, I'll need some help. I'm posting what I have by now after a day of work and noting broblems I ran into(I'll also update problems once they arise). The map is meant to be skecth-type black&white. Advice, criticism and links to relevant tutorials are highly appreciated.

I'm really new to mapmaking. By that i mean that I have an astonishing two days of experience. I'm not too proficient in Photoshop either. I used tools(brushes) I've found on the web.

1. Rivers. That is the biggest problem now. Whatever I do they just do not seem natural. Drawing them with a single-weight brush tool doesnt seem good.
2. Sea texture of shorelines. Added a sample of what I'd like to make(but I do not know how to make it in PS).
3. I have a desert planned(the blank zone under the huge forest ontop), but have hard times findeng PS brushes that can help me with it.
4. The large island on the op right seems out of place(like falls off the whole style of map) and I'm thinking of what better to do with it, so I'll gladly hear tips on that as well.

Thanks in advance!