SEO/SEM

I'm looking for someone who knows how to optimize websites. I run various German affiliate sites and I am looking for someone to optimize the site for Google search, so that the pages are found under more keywords and that the search terms are optimized.
Furthermore it is about the increase of Traffics, development of the Backlinks and graphic optimization of the side, as well as optimization of the performance.
All page are in Wordpress with a special theme.

Necessary knowledge:
-Knowledge in SEO / SEM
-Wordpress
-Onpage and offpage optimization
-Backlink construction
- Own ideas for optimization
-all sites in german

I am a private person and can not pay very much at first but with a good cooperation, scope and amount can be expanded.

Thank you

Oliver