Yea the volatility of the altcoin maybe is the key factor for trading but there are still 3 important questions we can ask for the trade.
1- Which altcoins do you prefer for your daily or short time trade generally?
2- And why do you prefer?
3- Do you have any daily income goal or you trade as much as you can with this altcoins?
IMO best coin for day trade are:
Litecoin and Etherum - high volume and pretty big stability
allso using them you can use laverage in some places for trading.