Where to start?

I've never used any sort of 3d program except blender (just pressing random buttons with no real purpose), and don't really know how to do any of this. I'd like to print models for personal use (1/58, 1/100, and 1/10000(Starships)), what program would be best to do it? For making both ships, tanks, and infantry models?

Have a look at Sketchup or 123D. Both are free and relatively easy to use and learn.

Woah that was fast. Thanks a lot I'll take a look for sure.