For me, it is very strange that your portfolio lacks Bitcoin and Ethereum. In my opinion, these are the two main coins in any cryptocurrency portfolio, which can now be bought at a very favorable price. You don't have to buy 1 BTC, just divide $600 into these coins.
Yes I am gonna buy 300$ Ethereum and 300$ NEO and then next month will get 600$ worth of bitcoin as well, and then continue building my altcoin portfolio and increase holding in Ethereum, Cardano and Ontology