Ideally you should never take a loss because eventually there may be a pump some day in the future and if you have sell orders set you will make your Bitcoins back or profit.
But like most rookies I bought POT coin when I first opened a Bittrex account. I bought it at the top and it has gone down, down, down.
Now I realize that when you buy at the bottom, you never lose. It's part of my strategy.
P.S. - I did buy some SMART coin before I saw your post and made my crypto back. Now, it's ALL Profit. Plus I'm holding 4,000 in my SMART Web Wallet.
Nice! It's super fun to get your investment back and have profit left over to play with. I did the same with PIVX and it worked well for me.