There are some exchanges that has gained reputations already although in cryptocurrency nothing is 100% assured but it's the closest you can get in being safe. Except you have other illicit motives like trying to double your coin, get it lower than the normal price and more.
Then you seek p2p which is still not safe even with the employment of an escrow agent there are cases of escrow agent defrauding individuals. It's just safer to get coin from exchanges that are of good reputations