The basic rule of thumb for cold composting is to keep a 3:1 ratio of brown matter to green matter.
Brown matter: fallen leaves, pine needles, shredded paper, and wood chips or sawdust from untreated wood, straw (never hay, as it contains seed heads), dried and dead weeds (again, without seed heads).
Green matter: grass clippings, garden trimmings, green weeds, kitchen scraps, and cage litter from small pets like rabbits.
Easiest: Throw your scraps on the ground!
Also easy: Compost in a hole and plant seeds right on top!
Lots of bin ideas using wood, concrete block, buckets, trash cans, etc.
Rolling composter bin that turns easily on small wheels:
Build your own double composter!
Build your very own worm composter — these are great for small spaces like garages.
Build new beds pronto with Lasagna Gardening or Sheet Mulching