When I have some coin wallet or market showing RED signal I can't stop myself to buy a coin. But maximum time price goe's deeper. Lot's of time it's happening for me, maybe the same story happens to you.
So let's start discussing what factor need's to check like Volume, moving average, price history etc..
When trying to buy an altcoin when there is red signal,then you have to be much cautious.Buying a coin when the price falls is not a bad idea.But you should get caught yourself by buying a coin which has been earlier pumped and now getting dumped.You must check its previous price history.
If you still find it to be an under valued coin,then you could buy it confidently as its price would increase in future.Otherwise,just stay away from it.