Coins like BTC and ETH have proven beyond reasonable doubts that they are the best and more safer coins to invest. My little advice is that, whenever you get your altcoins, it would be better to convert at least one third to either BTC or ETH to serve as some form of insurance to your tokens in case it fails to survive. I used to keep all my altcoins and now that the market is red it has badly affected my investment. And mind you, those new altcoins are not like BTC and ETH, they can get zero volume anytime so they are not reliable. Is there any other person with a different view or everybody agrees with me?
The answer to this question will of course depend on the project. If I get a good quality project income, I usually favor not to sell it, but if I find that the project is of poor quality, or if I cut my hopes from the project, I usually prefer to immediately change it. Very rarely when I need the money, I do not like it anymore but this happens very rarely.