Big Enough
Your pics should be large enough to see the detail of what you've made.
Tips:
MTS allows images MAXIMUM SIZE of 1280x1024 pixels and 240 kilobytes with a MINIMUM SIZE of 800x600 pixels so you should be able to upload nice big pictures. See the information above under "Screenshot Basics" for info on taking larger pics than the game will normally allow.
Don't take small pics and just make them larger in your graphics program - this just gives you a blurry pic that's bigger in dimensions with no additional detail.
