I think it depends on business type. For example SAAS is a type of business that may need SEO but some Startups don't need it at all. You should concentrate on your ICP as a step 0. Having an understanding who is your target audience is the best way to start. As you will have this understanding you'll just have to find communication channels with these companies.
It would be great if you'll have your own website on the first page of Google as you'll be a living example of your SEOs efficiency.