Top 50 altcoins will have biggest gain when the bull run comes. You can't invest in all of them, just need to find out your favorite coins in top 50 and out your money in. Also, don't forget to put out a stop loss level, for holding i think stop loss when you lose 20% is reasonable.
Agree that the top 50 coinmarketcap has the chance to skyrocket, but I prefer at a low price or under $ 1, because cheaper prices are easier to skyrocket when the bull is coming.