What you need to ask your SEO professional? You should make sure that you hire an ethical SEO Professional who will oerform only proper and guaranteed high quality seo work on your website. Unethical or bad SEARCH ENGINE OPTIMIZATION work, where efforts are made to unnaturally or inaccurately improve the success of your website on the Search results are absolutely frowned after by Google leading to penalties, or worst-case-scenario, being banned from Yahoo. This is extremely difficult to recover from and in worst cases the domain name should be forgotten. These practices include buying link, participating in link farms, cloaking domain brands, making text on your web pages noticeable to Google only and creating other content for Yahoo only, and not humans.
Search for SEARCH ENGINE OPTIMIZATION testimonials on their website and check them, and actually ring these clients and verify the success of the work that your potential supplier has done. Ask your provider for a set of activities they will undertake within the SEO of your website and check that no unethical activities are included. If in doubt ask me. If they subscribe to an SEO code of ethics of some sort, then that is desirable as well.
Regular progress updates, or questions from your SEARCH ENGINE OPTIMIZATION supplier contribute to knowing about it of the work achieved and is also valuable, as is your considered response to questions and feedback when requested.