Check Crypto Compare, Coinmarketcap and similar sites and decide on altcoins to invest into. You want coins that have not been pumped recently, are not at all time high and, most importantly, show potential for future growth. You need to do a lot of research. If you pick right you can see large gains (OMG doubled in value in the last two days), but be prepared also for fast drops. Do not invest what you cannot lose.