Yes, keep track of changes.

Something easy I do is simply submit my webpage/s to Wayback Archive before I make changes, this way I have the old version of the webpage saved online with almost no effort.

To submit a page to Wayback, go to their Home page and paste your page URL in the text box on the right side of the page. Click the SAVE PAGE button.

I didn't know you can submit your site to archive.org I thought they only crawl your site.

Thanks for letting me know.

Surely! If you make lots of little tweaks and changes, that would be rather hard to relate any impact to a specific change if you don`t keep track of them; I`d totally recommend to make notes. Also, a nice tip to keep to the older version of a page by submitting it to Wayback prior to updating. I personally mark the changes I make right on progress graphs in my rank checking tool - each one overlays the rankings and traffic graphs, so I can easily see if any changes match any leaps or spikes in my positions or visits.

I dont bother with so much. Coz i end up spending months on each of my sites. As long as you remember the major changes, everything will be fine.

Write Down in sheet all changes. If your changes is not work then update all keywords.

Your question reminded me of my grandmother who died 20 years ago, and who left behind thousands of hand-written pages about every day of her life.
He was a trully bogger, before blogging has even been discovered.
Since I've found those notes, I believe, it's impossible to write down your changes and actions.
So, yes, Julie, write them down!