Before investing, make a thorough investigation in the coin you are investing in and do observe the coin's statistics for atleast one year. Also, try investing in the top 10 coins as they are the least risky coins and are no longer considered under a financial bubble which can burst.
You can consider Ethereum, Bitcoin, Litecoin for your portfolio as these coins are well accepted in the financial market and have great prospects for the future.
in my opinion, before we invest in crypto we must know what crypto is and how it works. before we know what crypto is, don't invest once. if you don't know what crypto is.