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Good advice. When there's a potentially large impact (organic makes up such a large percentage of your traffic) you really do need to tread carefully. I've seen more than one site that rolled out sweeping changes in, shall we say an overly enthusiastic manner, and accidentally remove themselves from search completely! I would recommend doing some research and identifying the real low hanging fruit. What queries/topics/categories is there the greatest search opportunity. If you're already doing well for particular terms then there's not much scope for improvement and the impact of getting things wrong is worse. Can you look at particular pages that are performing badly. Look for landing pages for organic search traffic that have poor engagement metrics. This can identify poorly targeted keywords, or missing/poor content, miss-understood search intent etc. Make sure you document everything (with dates!). Don't try to do too much too fast. Small steady tests are safest and make sure you give your changes long-enough to see any impact. Make sure you have some kind of QA. Run checks before and after you make your changes. It's great if you can have some kind of check list. Watch out for unintended consequences. Are you tinkering with the live site or is there a development/deployment process you need to follow are there other people involved? If there is - stick to the process.