Or, even better, use a decentralised exchange (where they are available for the coin you wish to trade) - this means that the coins remain in your own wallet until you trade.
But what do do you do if you want a coin that is not traded on a decentralized exchange? I went to coinsmarkets solely for one coin that was not listed anywhere else at the time. But in general, you are definitely correct!
Yep, the only reason I ever joined coinsmarkets was exactly that. If I wanted to trade a hot new coin that was the only place it was available to do so.