It's not enough having an investment plan, knowing the right choice to make for every investment defines the investor better. Take for example jumping on every new coin we find on reputable exchange might not be enough guarantee that coin will do well in the future.
Because an exchange lists a coin/token doesn't guarantee the viability and success of the project. This is why one must learn, and research the coins/tokens they would want to purchase to at least be sure if they are worth it. But still, the listing of coins/tokens by Binance has ever been productive recently and my hesitation, just like your advice states, has deprived me of the huge money I would have earned.
Some coin might have good Supply but low liquidity, some might have high market capitalisation but very poor volatility. Although it's hard to predict the accuracy of a coin performance in the near future this why it is always advised to stick to the known which is BTC.
We should not think too much, and my advice is that once it's a good project and our chart is bullish about it, then we can buy it. In the bid to be too perfect in the coins' selection, you might make more mistakes. The coins/tokens with much more supply than demand often adjust the narrative over time, so we shouldn't be too rigid with this.
Another option is to spread ones portfolio amongst different coins but ensuring the have a greater percentage in projects with a visible future. It is better to win small and lose less than lose more and win less
This is the best of them all, portfolio diversification has helped me in the world of investment, and the more you do this, the less likely you lose. Still, one should learn the projects they would commit their money to, and if that done, there is likelihood that all the investments would be positive.