Be careful of scammers trying to get your bitcoins. They will claim all kind of impossible things like doubling your bitcoin in 30-40 days. That's impossible. Last week i found this site :
http://www.badbitcoin.org/
It's not perfect but at least it gives you a good ideas of the insane amount of scammers out there. Before you send money to a site, maybe sure to check that site. You can also report new sites for them to add. That 30 seconds could save you a lot of money.
PS : I'm not affilliated with that site, i'm just relying that information.