There are two basic things that need to be implemented when the market suddenly falls like yesterday to make a profit. First, the attitude must remain calm by thinking that it will recover. Second, take the opportunity to buy as many coins as possible, such as top 10 coins.
I agree with you that when markets tank, the smartest thing to do is NOT panic and stay the course. If markets tank, it sucks, but it shouldn't be too big of an issue due to the fact that if your portfolio is properly established, then you're prepared for things like this. As for your second part, buy as many coins as possible such as the top 10..the top 10 is littered with garbage coins with NO future..buy coins that solve a legit need right now such as bitcoin and ethereum.