You need to monitor the prices all the time. You can set an alert when the prices go above where you want to sell them. Or you can buy more when they go to a really cheap price.

There is no rhyme or reason with stock prices, including crypto.
Hodling is a long term strategy, like holding on for 10 or 20 years.

My main suggestion would be to start playing Steem Monsters and then start buying and selling cards through Peakmonsters.

I have an affiliate link here.
https://steemmonsters.com?ref=bluesteemie