I've listed 25 different tarp shelter designs to help you get started. Each configuration has its pros and cons and there isn't really a perfect design for all occasions. You'll have to chose the right one depending on your situation.
Tarp Shelters - Examples showing how to make multiple types of tarp shelters. With a small amount of paracord and a tarp, you can quickly setup an improvised shelter that will keep you dry and warm with a small reflected fire.
How to make a Tarp Tipi / Teepee Survival Tent Shelter – Backpacking
If you need to pitch a tarp or tighten a fly, you can make an impromptu tarp clip from a split twig, a matchstick and a bit of string. Works best if the clamping part is long enough to go over the folded edge of the tarp.