Go to the source - i.e. monitor government sites that list new company incorporations and then call the companies with your pitch. In the US that would be the Secretary of State website for each state.

I exclude the geographical condition for the answer. To sell your services to potential customers, you must be clear about who your customers are according to your product, without delving deeper. Is your customer for your product a B2C or B2B customer? Once that is clear, you can determine what your customer is willing to pay by checking the price median for similar products in your target country or area. That gives you the price range. Then, consider why the customer should buy your product specifically. What differentiates your product from other providers, and why is yours better than the others? Write down all these points and put yourself in the customer's perspective to consider whether you would buy this product.

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.

I can share my framework we receive 2 leads a day from my organic growth systems (free marketing channels)

"How to find my potential customers".... the questions is like how far is a tread as we say in Sweden.

Option with sales consultant is you want to have some goals and groups to target so they can be more effective. A good sales consultant should also be able to find some relevant sources too.

Option without sales consultant.

How much work are you willing to put in ?
I would start with reverse engineering.
Look at current companies in similar area on e.g. LinkedIn and see which companies and people they interact with this will give you initial clues.

Depends on which segment and level of companies you want to reach out to. I would say just be bold and dare to contact the larger firms also. Focus on building relationships not only selling since some of them might not be interested in the long run but they might consider you in the future.

E.g. do you want to be a premium level provider or a midrange or cheaper and have more volume on customers?
Got to start somewhere right, but don't get stuck on the wrong end if you want to be a premium level.

Google tools and relevant communities for SaaS and Startup companies might be go. If you're able to do few gigs for references.

Let me know if you want to follow up there are so many options it's just based on which options you consider more fun so you can enough during your journey.