Where do I start with a Content Audit?

I’ve been asked to do a mass content audit of my company’s website. We regularly publish 5+ blogs a week (sometimes 10), so there are 100s of blogs.

I’m a copywriter who follows SEO on-page best practises but I have little knowledge on this kind of thing.

What steps would you take and where would you start? I’ve read a LOT of info around this but am honestly struggling to find a starting point with what content to audit first/should I use a tool?

Ultimately the goal is to drive more organic traffic and raise conversions, but we need to do a ‘keep, delete, update’ assessment first.