Main bitcoin scams can be some untrusted sites asking  for some investment and in return give some amazing and exciting offers .
They will come up with some message or pop-ups such as " you have won 20 btc " to win them provide your private access of your wallet . Such attempts clearly indicates that there is something wrong in them . Falling for such baits can lead to a heavy loss as you provide them with your direct access to the wallet .
Do not share your wallet details with anyone . I know "20 btc" is very tempting but turning for such temptations can be the worst turn you might ever take .