My personal strategy is to hold 5-6 of the more well-known, long established coins like ETH, Dash, Zcash, Monero, BTC, and LTC.
Beyond that I'm only investing in projects where I know someone personally, or where I see that the token is not simply grafted onto a shit business plan. Especially if the token has value sources that are relatively stable, I will consider holding it.
It's better if some of this coin are used to buy bitcoin, because holding a lot of ethereum is too much risky. Since this altcoin are starting to fall down their price in the crypto currency market. Therefore if you want to invest it into other altcoins there's a lot of trusted coins in the market like bitcoin cash, bitcoin gold, waves and so on.
These are good examples of coins that they want to hold in the future, definitely I have some numbers of these coin and I still holding it because I know that some of this day value of these coin are incredibly increasing.