I don't suggest that you trade with all of your coins. It's best to hold a portion for a long term investment. I suggest holding 50% or more and trading the rest. One of the main reasons for this is that you can't fully trust exchanges. They could get hacked or just steal your money. It's happened before with MtGox, Cryptsy, and others. Also with trading you have potential to make more profit but you could also lose out on big gains if you sell and the price keeps going up. So there's no guarantee that you will make money trading.