You've found a campsite, staked out your territory and cleared it of any unwanted debris; now it's time to actually set up the tent. Depending on what type of tent you have, you should lay a waterproof tarp or cloth down on the ground before you get to work fitting the polls together and stretching the canvas. A ground cloth creates a thin barrier of protection between the bottom of your tent and anything beneath that might puncture the tent. It also prevents ground-level condensation from getting in. The ground cloth can have other uses, as well. Under certain conditions, the tarp can be used as a rain shield in your cooking area, for example, or you can create a separate low-tech shelter [source: REI].
After setting up your tent, be sure to put an additional tarp or rain fly on it. A rain fly is a waterproof tarp that fits to the outside of your tent. Even if rain isn't in the forecast, it's a good idea to set up the rain fly, because it will also keep your tent dry from dew. If it's windy, it's probably a good idea to stake the tent down to the ground to prevent it from blowing away. After going to all the trouble of setting up a tent, it'd be a shame to let it blow away! If you don't have any stakes, or if the ground is too rocky to anchor them, you can tie the tent down to nearby trees (but be careful not to trip over the ropes).