The two fixes that matter most
1) Title tag rewrite — most pages have generic titles ("About Us — Acme") that don't include the keyword they're trying to rank for. Rewriting the title with the keyword near the front often moves rankings by 2-5 positions within a week.
2) Content expansion — pages ranking 8-20 are usually too thin. Adding 500-1500 words of useful, on-topic content (not filler) and a few new headings often pushes pages into the top 5.