When choosing an SEO agency, there are a few key factors to consider. Here are some to keep in mind: 

1. Size and Experience. One of the most important factors to consider when evaluating a business startup SEO agency is their size and experience. A smaller agency may not be able to provide the same level of service as a larger one, and a new company may not have the requisite experience to achieve top results.

Image Source:Google

2. Cost and Duration. Another important factor to consider when evaluating an SEO agency is their cost and duration. While some agencies may charge more per hour than others, all should be transparent about how long it will take them to achieve your desired results.

3. Expertise and Backgrounds. When evaluating an SEO agency, it's important to look for experts with backgrounds in digital marketing and search engine optimization (SEO). This will ensure that your website is given the best opportunity for visibility online.

4. Track Record and Client Feedback. Finally, it's important to review the agency's track record and read client feedback in order to get a sense for their quality of workmanship. While there are many great agencies out there, if you don't feel confident after interviewing several candidates, then steer clear! 

While these are just a few key factors to keep in mind when evaluating an SEO agency, overall, it's important to do your due diligence and assess each candidate on their individual merits.