Where to start to optimize a forum?

I own a MyBB forum. I have installed SEO plugin to make it user friendly and to have a sitemap.
These are the features:

• Google SEO 404:
  • Error pages return HTTP 404 Not Found (and others) instead of 200 OK
  • Custom 404 error pages
  • Google's 404 widget

• Google SEO Meta:
  • description meta tags for forums / threads / etc.
  • specify canonical pages
  • nofollow links

• Google SEO Redirect:
  • redirect old URLs to...

Where to start to optimize a forum?

from Search Engine Optimization https://ift.tt/2NdjdyA
via IFTTT