I always buy coins when they are at dip. I haven't really invested into coins when they are with a good value, always looking for some which are at a slight downfall. You should never really invest into coins which aren't at a dip. Now I personally won't invest into anything because I'm waiting for my other investments to rise so I can enjoy my money for the summer. Right now is definitely the best time to invest into altcoins, even into Bitcoin because I hear a lot of people are expecting a big value increase.