You missed the most important:
#1 leave your money on an exchanger
Yes, and i think that is the most important thing that any bitcoin user must know at the moment he introduces himself to bitcoin.
I had to learn that by the hard way, i was just trading in a local exchanger, and i left there 0.03 worth of some altcoins, that is not too much money so i was lucky, but the exchanger dissapeared a few days after.
I think that leaving coins in any exchanger is risky, doesnt matter if its poloniex,bittrex, or any other that offers "trust" they all are the same, it is better to store your own coins, and if you have ethereum tokens, then store them in your ethereum wallet, it is not too difficult and you wont risk too much.
Well that's so sad if exchanges will be disappeared a few days, so for me those mistakes made by bitcoin users merely not a good practices and should be avoided. If they continue doing it and not learning by the lessons from that scenario, I think they will become such a failure of bitcoin profit seeking opportunity for now. I agree that storing your coins at your ethereum wallets can be safer if you try to do it long terms and avoid storing at trading sites so that you will not be stressed thinking about the growth of your funds.