We should buy potential one and I personally suggest to buy BNB, Cardano, Cake, Dot, Matic. It may takes longer time to get a smart earning but it almost sure that you'll be able to get good profit. You need to analyze market before invest a coin to avoid risk.
the action that must be taken every time you make an investment or anything in crypto is clear as you said, first analyze it properly using existing mechanisms and there are enough analyzes that can be used before taking any action to be taken.
what is certain is that the coin with the best ranking in CMC or CG can indeed be used as a basis for making investments that will be made. If you have large funds, obviously I prefer to invest in ethereum, but there is no harm in BNB, ADA, SOL, DOT which have great potential and Matic, SHIB which has been a surprise lately.