Factor in the added gas mileage of towing a camping trailer. Depending on the weight of your trailer, the gas mileage of your vehicle may be very low, causing you to spend more money on gas.
Ensure the campsite you choose allows trailers. Though most campsites allow and encourage the use of camping trailers, there are still some that don't allow them.
Research the features of your trailer and determine what hookups it needs, and then check to see that the campsite has the required hookups for your trailer. Many camping trailers just require water, but depending on your particular trailer you may require additional hookups.