I've earned a lot of money betting in cs:go and I know about many people that has earned a lot betting in this matches.
I have bet mostly skins of the games in csgolounge.com and sometimes btc in nitrogensports.
I open this thread to talk about predictions.
Some good sites to track stats of the teams are the following:
http://www.csgonuts.com/ - You can compares stats for the teams, including their better maps.
http://www.gosugamers.net/ - Rank/Information about net matches
http://www.hltv.org/ - Net matches map / players that play / standins and news.