Predicting sites are helpful most of the time when you know what you are doing. If you don't have a clue on how to predict, I will advise you to take a lesson on that first. 
 
What I usually do with prediction sites most times is to select a few sports games and compare them with my own predicted games. Most times, I don't even use any of the options because sometimes we might be on the same line, which will be an all-go-in for me.