On-Page SEO Revamp Needed

My site is ranking lower than it should, so I’m ready for a focused on-page SEO overhaul. I need someone who can dig into the pages that already exist, polish every word, and also craft fresh pieces that fill our content gaps... (Budget: $10 - $30 USD, Jobs: Analytics, Content Strategy, Content Writing, Copywriting, Keyword Research, Link Building, SEO, Website Optimization)