Don't make 32x32, they are too small and don't give enough space. Heres a tip for good map making: include custom resources 1-3. You only use 1 and 2, but some people will use a mod or different tech tree to add a new one, and it's annoying to fix it up (I had to mod every map in order to allow herbs for my ancient tech tree)
Also, make sure that if they have narrow passages, you can fit all units through. (Make sure large units like the golem fit)
If you want to make a trench, use custom object 4, which is generally a large stone witch blends with others. (makes great mountains)
Try those tips for better maps.