Diversify your exchange platforms but also your wallets. This might apply a little more to someone who holds a large amount of different coins, and is tech savvy, after all managing your wallets is a skill that takes time to learn. Whatever a beginner might do, the main point should be to avoid the habit of leaving their currency on the actual exchange site. Learning coin ownership is a must, and it requires having an understanding of what an address really is and everything a transaction entails.

Paper wallet for optimal cold storage, for everything else a hardware wallet like a trezor or nano--then maybe a mobile wallet for convenience/liquidity--if necessary.