There are a whole lot of survey websites out there. Some are better and more reputable than others. I’ve dabbled in three: e-Rewards (which gives Velocity points), Red Planet (Qantas points), and Mint Surveys (Coles gift cards). In my experience, e-Rewards is the least worth it of the three. They give the fewest points, and their customer service is the least efficient (it once took a full two months for me to receive the Velocity points after I asked for them).
My subjective, personal opinion is that Mint Surveys is the best and most well-run of the three, with Red Planet not far behind. Unless you must absolutely have Velocity points, I’d look into one of the others if I were you.
You might also like to have a quick skim of this Point Hacks article from a few years ago.