The taut-line hitch is an incredibly useful knot for camping. It can secure a tarp to stakes, or make a rudimentary clothesline. However, for heavy duty use, something like the trucker's hitch is recommended.
Step 1: Prepare to Tie
Securely fasten one end of the rope to whatever you need to pull tight. Then take the other end and loop it around the object you will be tying the knot next to. Proceed to the next step.
Step 2: Tie the Taut-Line Hitch
Make a turn around the object several feet from the free end. Coil the free end twice around the long end working back toward the post. Make one additional coil around the long end on the outside of the coils just made. Now tighten your knot and adjust the tension as needed.