You have to buy currencies after they have been listed on the exchanges, and first monitor market movements and technical analysis, this will be safe for you as well. You can also buy currencies of top value and you may wait for months or years until you get Rewarding profits, but this choice will be for beginners who don't have experience in hunting promising new projects.
This will be a recommendation for beginners to minimize the risk of loss, by buying coins that have been exchanged, they will think that these coins have been traded by people. usually for beginners they will make a simple decision to be able to buy a high volume of coins, maybe it was done because of an invitation from a friend or because of seeing the growth of the coin itself.