You can try faucets, but you don't really get much bang for your buck. I've been using https://freebitco.in/ on and off since January, my balance is at 0.0063 bitcoins, you get the idea. When your membership level allows it, signature campaigns can give you a small compensation per post, but it still wont amount to a lot unless you spend a lot of time here and post a tonne. Which can run you into problems with getting banned if your post come across as spam, or posts that don't contain substance.
You can always try you luck at dice sites, like Pocket Dice. You may get lucky, hard to say. Nothing is free though.