Hey Straf!

I mostly like what you're doing there. Especially considering you're doing it with just a mouse. When I started out, I didn't have a lot of experience and wouldn't consider myself an artist aswell, but although I still wouldn't consider myself one, I found that one can progress a lot by just H&H! If you're really into it, consider investing in a graphics tablet. It makes work so much easier and accessible.

If you're using textures, Caenwyr already said everything there is to know. Only use the right resolution and only use free ones or your own. There are some good tutorials on creating your own textures on the forum, maybe check those out.

As for your map, I really like what you did with those mountains, it reminds me of what i did at first. Your coastlines are a bit thick, though I like their raggedness. The colouring also is a good start, but it looks a bit blurry.

Lastly, have some rep for all the work!