In trading in crypto, choose popular coins, of course we can choose the top 10 coins, because it is safe. and we will not lose when trading like losing money when gambling. In trading in crypto when the market is experiencing a price drop and we are trapped, it is better to hold and wait for the market to rise again.
For experienced traders, they won't only choose popular or top coins. They may prefer choosing the trending coins that have high volatility. But it will be riskier because the prices move quickly. For beginners, choosing top coins is the best option. It will be safe if we choose top coins, the chance to be dead coins smaller. Sure, if we choose top coins, we can keep them on the wallets if we unsuccessful sell them. Keeping top coins will be safe both for a short term and long term. 
It will be more save to trade with old coins they are more better and you hardly lose money when you are trading on old coins such has Bitcoin, Monero, Litecoin, Dogecoin, and Ethereum, a friend of mine who is a trader was telling me that the most money he has lost is trading with all this new coins he said as a trader if you want to play a safe trade is better you trade with old coin he also said the coin that has given him much profit in trade is Bitcoin and Bitcoin is the the first crypto coin to be created and the best crypto coin in the world, Bitcoin has made a lot of people Rich and should be taken serious.
However some people prefer to trade with coins with very high volatility in other for them to make profit quick and this kind of trade is very risky because you are never too sure what will happen, but for those who has been into this trading business for years they understands how they market will turn out because they have studied the coin very well and how much interest that is in that coin and with there past experience they will be able to determine the coins price at come in the next one week and that is why i say trading is not a game of luck it takes study and experience to understand cryptocurrency trading very well, a friend of mine when he started crypto trading he lost a lot of money but when he became more experience he started gaining more than he was losing, if you understand it very well you will succeed in it.