On my personal experience short term investment in alternative coins is trading altcoins with use scalping strategy, it is mean we just take the profit around 5-10% from the capital to be used to investment based on the capital, i traded alternative coins on binance.com and bittrex, i choose ripple, waves, nxt ethereum classic ETC, BTG and another alternative coins that has up trend in couples weeks later. You just can make target how much the profit will be taken on couples weeks and always taking profit daily.