The answer depends on how old your page is, and on how high your page currently appears in Google search results for your main keyword phrase.
If your page already appears quite high in Google for your keyword phrase, it's best to make only a few tweaks at a time. This way, if a change negatively affects your position, you will know what to put back.
If your page is new, a good strategy is to first do enough to appear in the top 100 Google results. Getting a score of around 75% will usually be enough. Once in the top 100, make a few changes at a time so that you move up gradually. Once you get more comfortable with SEO and using POP’s recommendations, you will better understand how ambitious or patient you need to be in your SEO work.