for other altcoins try to pay attention to them in a much shorter terms, it can be from only a couple of days to 1-2 months tops.
check out those coins that are hot at the moment with high trade volumes (high liquidity) and try investing in those.
for example litecoin is one of those coins that you should conside as long term but ethereum is one of those risky pump and dumps that is only good for a very short time.
I really appreciate your kind suggestion ! I also think BTC is worthy to buy and keep . Thank you very much !