You will be constantly bombarded with emails offering you search engine optimisation (SEO), link building and link exchanges. These are 99% worthless and can often damage your search engine results through dodgy practices designed to offer short term gains.
Search engines are continually clamping down on junk blogs, affiliate schemes and other worthless sites, so using cheap SEO services can damage you long term.
If you want to outsource your SEO it's best to get recommendations off people who have used SEO companies. We can recommend several local freelancers who can help you improve your rankings.