I can recommend you try with ethereum now. Its price grow very fast and high so if you want earn some coins for your investments on 2018 you can buy few eth and wait when its price achieve 1000 dollars. It will be easy
+ 1 on this. ETH is in the middle of a run currently. If it has the sort of run that LTC just had, then watch out... You can park your money in ETH & then buy your alt coins with your appreciated ETH once you're ready to "sell".
One more +1 here. You can just put 90% in Ether and use 10% for coins you expect to grow x10. Personally with such movements of top 20 I would not expect such growth to happen. But anything can happen - especially short-term.