One of the most important things to do is to "Get all details in WRITING".  Usually by asking as many questions as you can, getting the answers to your questions, job duties, pay, hours, campsite, and perks in writing will help eliminate problems. Since you maybe driving hundreds or thousands of miles to reach the job at your own expense  make sure you understand exactly what the employer want from you and get the details in writing. Be sure that you know exactly how many hours you will actually be working for the site and exactly what your duties will be. If you will be paid for hours over those for the site, make sure it is an hourly wage.  If they are quoting a monthly "salary",  you may find that you are working 60 hours a week for $2.50 an hour.  If you are happy with that then that is your choice.

When reading the ads, be sure to read between the lines .... what are they really saying?  By asking lots of questions you can avoid a bad situation but if things don't work out, try to work it out with the employer but if the employer will not work with you, you can always (just like in a regular job) give your two week notice.  This gives the employer time to find someone else.