Firstly, you have to think of how long will you plan to hold that particular coin.
Second, how much money you will going to invest on that coin.
Third, do some research about the coin that you're going to invest your money on it.
Golden rule on investing 'Invest what you can afford to loose' and 'Don't put all your egg in one basket'
Hope it helps you mate! These question like you is already asks here again and again.
Do Your Own Research (DYOR) would be the best thoughts I can give to you sir !