for the best type of volatile coin, I think there is currently no better coin than bitcoin and ethereum in the matter. Besides, the volume is also very large, so it might suit you.

for bitcoin, currently the range of ups and downs is $44k to $47, and it is estimated that the price will rise in the range of $50k. if you choose this, maybe the safe low is $43k, if the price is lower than that, I suggest selling.

while for ethereum, the ups and downs occurred quickly in the $3k and $3.3k range, the lowest selling point was $2.9k.

You can see the chart for the last 7 days on CMC