Make sure we always hold bitcoin before any coin in our portfolio. I won't forbid investing in any altcoins, but don't let us forget about bitcoins and instead focus on altcoins alone.
I usually make bitcoin my top priority, and if I want to invest in altcoins, I only share a portion of my capital in a percentage that is not much more than bitcoin. And even if I want to invest in altcoins, I usually don't focus on one of my coins, but I spread it from my capital for at least 2 types of coins.
If there is a desire to buy altcoins, then the maximum you can allocate for this is 10% of your portfolio, but personally I would not do this. If there is bitcoin and I am confident in it, then why should I buy other coins?
I doubt that in the end these altcoins will grow significantly higher than bitcoin, but at the same time there is a very high risk that this altcoin may not grow, or something will happen to this project and its price will fall significantly.
Even if I know that bitcoin will grow a little less, but I will be sure that this is a reliable investment and nothing bad will definitely happen to it.