Opportunity Product History Tracking

Hello everyone. I found this useful posts like this one (https://www.forcetalks.com/salesforce-topic/how-to-track-field-history-on-opportunity-line-items/) to help me set up a trigger to track Opportunity Product field history.
I’ve got it working for one field on the Opportunity Product, but there are several fields that I want to track history on. How do I modify this apex trigger to track multiple fields, not just Product Status? Thank you!