One important ting to keep in mind when using btcoin.
don't send you btc to any one before confirming that you got what you want in exchange.
multisig is good but not that much populor and need to rely on third party.
Don't don't share your private key with any one. it is very important to keep is safe and only you have an access. don't put it on your pc. which is coonected to net. or put few btc that needed to use in the pc wallet else keep your btc at safe place.