There are no set rules on how to do this. Early on, many companies do this because they do not have the $$ to pay for services. I think doing this is smart, and is a true example of the Hustle.

Start with how much your service is per hour/gig/whatever metric you want to use. From there, be open to hearing what the similar business charges. Star there.

One of my favorite parts of bartering services is the potential to evaluate future partners with opposing skill sets. You get to evaluate many things from the timelines of the their work, quality, etc.

This is a broad question, so let me know if you would like to hop on a call to discuss this further. I would be happy to chat and tailor the answer more towards your specific business.