Watch out for extremely low prices: Websites offing a $9.99 one time fee for unlimited movie, music and video game downloads is clearly not giving you quality downloads. Sure it's cheap, but you get what you pay for. Yes, they have thousands of movies, but who wants to watch no-name movies from the 1980s?
Look for reputable websites. By that, I mean media website that is not heavy on flash content, not just one large image and has a limited amount of banners. Be wary of pop-ups from other websites that are trying to advertise cheap movie downloads. Often times it will lead you to an unrelated website or a cheap vendor.
Do a search for "reviewed movie download websites." Many authors and users have created websites to review the best companies to download the movie from. many people are tired of being scammed by all of the advertisements bombarding you each day. Read their reviews carefully and make an educated decision for yourself. People will go out of their way to spread the word about a good website, just like they will about a poor website.
Find a website specific to what you are looking for. Rather than look for a website that claims to have it all, look for a category specific company such as movies, music or video games. At least look for a website that specializes in one of those categories. Such as offering an assortment of movies, but also giving you access to music and video games. You will greatly increase your chances of finding quality movies.
Fmovies is a website that shows streaming full-length and uncut free online movies and free TV shows.