Looks good for a first map! A few things you might try:
- put a white stroke around your text and town symbols (using layer styles)
- possibly change the font as it's a little hard to read
- add some soft texture to the ocean
- use the same layer style for lakes as you did for rivers
- spice the terrain up with some additional hues/colours
- the texture you're using for the green grassy lands has a lot of straight lines in it. possibly change it to something more random?