1.) When you first start out it is worth taking all of the surveys you get even if they are not paying surveys. Many of the sites use these non-paying surveys as screening surveys that lead to paying surveys. If you skip over the "screening" surveys some of the sites drop you as an unreliable member and don't send you the paying surveys.
2.) There is a high probability that you won't qualify for quite a few of the surveys sent your way. Because of this, it is wise to sign up for many of the free survey sites so that you can keep a steady flow of paying surveys. At times you can have a large amount of paying surveys to complete, and at other times you will have a drought.
3.) Keep up with your surveys. If you receive a paid survey opportunity, do it as quickly and diligently as you can. This will prove to the survey company that you are reliable and that you will keep up with their needs. The better your reputation, the more paying surveys you will receive. This is also important because many paying surveys have a cap on the number of people that can take them.
4.) Referrals are another great way to make money from these sites. If you have family and friends that are willing to take surveys, refer them to the pages where you've signed up and you will make money every time they take a survey as well.
5.) Don't breeze through surveys without reading the questions. Many of the surveys have quality control questions that will void your payment if you don't answer the question properly. Be as accurate as you can and become a reliable asset to the sites you've signed up for.