This doesn't really let people help you too much. What kind of maps are you interested in building? Aesthetic? Mini-game? Competitive? And what is it that you're struggling with? Ideas? Techniques? Inspiration? You should probably consider adding some more detail to this post. If you need inspiration it's a good idea to look at the world around you. There are often beautiful structures that can be recreated in forge to look great. Other than that, I can't help you too much - Sorry.
Wow contrary to the post above me i have 1 for you. I am not into forging at the moment as im playing just cause 2, highly recommended. But i had an idea a while ago for a map here it is. Now i have no fancy sketchup just a basuc idea. This map would be on the blue end of sandbox on the highly slanted side. The map idea is to have a slanted battlefield, with an oasis at the bottom with rockets or another power weapon at the bottom. Along the sides going up would be a series of tunnels and rooms. there would be a ring around the entire top level with an open view to the bottom where rockets or another power weapons spawn. i know it is wrong but i hope it helps, PM here or on xbox if you want help, ill try to be there. let me know if you do do this, cause i want some credit. GT TEH Wild Mudkip