The way volatility is going in the crypto market you can say buy and hold is a good option. But their are something to understand that don't buy at high because and what are you going to hold it have proper research it. Because if you buy shit and hold it you can loose everything and also if you buy at high still your capital stuck. So always take entry in dip.
You shouldn't buy low-rated riptocurrencies for long-term storage. It is best to invest in the top rated cryptocurrencies and after a while it will bring you a really very good profit. But in order to feel more comfortable, you need to have other sources of income, so that investment in cryptocurrency does not put much pressure on you and does not cause panic during a fall or strong fluctuation in the cryptocurrency market.
I don't know what you classify as "Low-Rated" cryptocurrencies but in most cases not all low-rated crypto are for short term, this certainly depends on our individual preferences but i believe there are many low-rated crypto that are actually under the radar, all we need is do a lot of digging to ensure that they are worth every scent of it,
And i do agree about sticking to top rated crypto in cmc because this top rated have a good track record and been around for some years, so they are safe investment, however, there are many undervalued crypto out there that are good for long term and can give good returns.