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It depends on what you want to do with them, for short term storage I'd say an online wallet of some sort should be fine if you want to sell it quickly and so on. Or alternatively for medium term storage look at just putting it on your own computer's wallet, for long term storage you could maybe looking at getting a paper wallet set up.

I usually just keep mine in Coinbase. The only time I keep them in Poloniex (or any trading platform) is if I'm going to trade immediately to another coin. I don't like keeping it in an exchange anymore because of down time and they require a lot more personal info if you want to trade higher amounts.

I am also curious. I have ETH and LTC on coinbase currently.