Storing your BTC on an exchange is the common way most traders save their coins. But is it the best method? Cold storage to me look expensive, since it is costive to purchase hardware.
Avoid keeping bitcoins in exchanges as they are more prone to cyber attack, put them in wallets.Different exchanges/wallets are CEX.IO , Coinbase , Coinmama , Whaleclub , Lake BTC , Bitit , VirWox , HitBTC, Changelly.