Try to select only those altcoins which will have reliable and known developers and will have a good number of investment and will have a good volume of trade.
Yeah these features are most affecting the value of any altcoin, coins with that features will have good potential to increase in value in the future so any person who will have investment in that coin will not be disappointed and will earn a good profit in the future when the value will increase.
not forever the alt coins are having a reliable developer will having the happy ending, maybe there are a lot of example like that. I think too difficult just considering about their developer. and there is no guarantee about your profit if choosing the altcoins with the reliable development.