The wisest thing to do when you have mutliple altcoins is to use multiple dedicated altcoins wallets and store them securly on your hard drive. But its inconvenient and what I do is divide it into two portions.

Bigger sums I store in dedicated wallets and smaller sums i keep online on Cryptopia account to make it avaliable for conversions. I know its not the wisest thing to do but so far everything was ok and the sum is not very big.