If the secret is to be early, it then means that the question should be, "how to be early"? It is not easy to find a coin in the early stage, even if one manages to find, how would they be sure that the coin will be prosperous in the future. As being told OP, this requires a high level DYOR and everyone has their personal means of doing their own research. What works for Mr A might not necessarily work for Mr B.
Well if for trading purposes there are tools to do that check the codes if safe, some websites upload new coins or tokens and details(purely minimal info). To answer the part whether its gonna be succesful is quite hard and not answerable by yes. Of course still 50/50 chance. Its still a risky play to be honest. Even on private deals, investors arent sure how good the performance of a newly sprung token or being introduced project. They will only felt it when its doing the moon mission.
I know that cause I invested on some of this so called early like the only details they have is a single tweet and nothing else. Its a matter of courage if you want to gain more and willing to risk too. Plenty of new projects and sometime you see them first hand if you knew where to look but it doesnt mean a guaranteed success though.