Personally, i trade most of my altcoins on Bittrex, as it find it reputable and simple to use. When I need or want to cash out, I convert them either BTC or ETH and send them to a smaller exchange in my home country. From this account I can trade either BTC or ETH for local currency fiat, and then withdraw it to my bank account.
Is Coinbase a good place to deal with?
I'm just learning this digital currency stuff now...
I bought some ether and bitcoin in Coinbase a few days ago...
If you have a friend with bitcoin that is the safest place probably. All these exchanges have their issues. I have used Coinbase many times they always sent my funds but I wouldn't leave money there or any other third party.
I do the same with Bittrex. And then I trade the Bitcoin in person, with people I know in Denmark.