How do we identify the best coin and the period to invest in these types of coins?
I think it's not too difficult and there are lots of tutorials that explain general things like this, but there are also looking for references from trusted and updated sources so that they are useful for your investment decisions. don't just rely on one source of information, compare it to other sources, then take a step and decide whether to enter or not.
If in doubt consult with friends who are experts regarding your plans and discourse. Simple i think.