From my relatively short experience on bitcoin world itself, i've encountered more than enough scam to gain some lesson related to ponzi and scam. All that I can tell you, the beginners, are:
1. Don't fall into big-paying-invest-method site. Mostly won't pay after certain period of time (this called ponzi) which exactly means you'll lose your btc.
2. Spare some time to do research, it'll save your time from solving captcha to accumulate satoshis which would never be credited to your wallet. Either googling the keyword "site name" + "scam" or search the "site name" on bitcoin forums, I believe there are many generous member who will post their experience with the site and give you some insight of how legit the site is.
3. Don't forget to have some rest

Any other tips experienced member out there want to add?