To be honest, I do agree with Ts4ever here. Although I do use different techniques with heightmaps.
Another thing to add to his posts:
Developing games whether it's mapping, modeling, texturing, coding etc will be one of the most difficult tasks out there. Even more so when you are just beginning. I remember I was just terrible at things, and when I started to quit, I somehow went back developing. My love for developing never left me. Maybe that's just me, I don't know.
One thing you have know in developing, it takes time; starting your map, model etc will look absolutely crappy, but with patience it will look a lot better. With time again, you will live to see the result of your very own project.
First things you have to do in your map in whatever game engine, is planning. Planning is everything, it might take the same time as you create your map.
You will learn many things as you go along, sure it's overwhelming but you just have to take a step at a time.
With these bumps along the road, you will gain experience, and that is one of the best things. More or less, without these bumps/criticism, you will never improve.
@Ts4Ever: I'm curious, did you Photoshop that T34 in?