Is it worth it to take the time to do these?
Yes. I would take some of them but not all. The non compensated surveys are screeneers designed to find surveys for you. The more they know about you the better the company will be at finding surveys that you will qualify for.
Is there a strategy to being a part of survey companies?
In terms of strategy consistency is my best advice. Setting aside time each week to take surveys is key. The other strategy would be referrals. If you are doing great with a survey company, share it with your readers (if you’re a blogger) or with your friends on Facebook and/or Twitter.
Referrals is an equal component to what can be earned taking surveys. 50% of what I earn each month from surveys is from referrals.
Finally, here is some information about surveys from my site if you haven’t read it.