Well, you can figure it out while reading some of the posts here and it is your job to find and sort it.
Because for me, you will only know when to buy when the price is dumping with some certain factors like e.g. fork, price manipulation(it is common), prices of altcoins started to dump when Bitcoin dump.
So their secrets are passed out or they are changing. If everyone who read this thread learn how to buy correctly, that will not effect the total community.
Anyway, I'm brave enough to share what I know.