Yeah, erickkyut is right. I also would suggest choosing an easy-to-use exchange where you can buy coins with your cards. Like CEX (https://cex.io/). This website provides a cold storage for keeping coins. But it's still better to have a hardware wallet for such purposes. Anyway, if the exchange has an option of a cold storage that means your coins will be placed in the cyberspace offline. And the exchange I've mentioned has a high level of security, so I'm quite sure you won't have problems with it.