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.
Well it sounds good and simple only in reality not very easy especially when the market suddenly falls, however, I do agree with the idea of buying more good coins when the market falls and the cash is available, market will always recover and you may end up in regret if you fail to take advantage of it while you can (meaning having some lose cash and refusing to top up because of the sudden dip).