[safety1st]

I would start with classifying these costs based on whether they increase as the number of paying customers you have increases, or stay roughly the same. Then focus on the first group and don't worry too much about the latter. So for instance an accounting SaaS may feel like a meaningful expense now but 10x your customer base and it won't, the fees may go up but relatively speaking not by a lot. Whereas fees to OpenAI can potentially be a large enough percentage of your gross margin to make the business nonviable at any scale unless you rethink it.

Assuming what you sell is a SaaS itself, you need to keep in mind that a good SaaS can easily have COGS of only 10-20% of revenue. They can then funnel a big chunk of their profit into marketing, grow, and if they're doing what you're doing, crowd you out of the market.

So you need to get as close as possible to that magic number of being able to provide the service at a cost of only 10-20% of revenue. You can do this by lowering costs or by raising prices (if your market won't tolerate higher prices, try and retool the service for a market than can). Get your COGS down and you will be able to reinvest the surplus cash you're generating into trying different marketing channels, with growth you will grow out of the fixed expenses problems that tend to come along with a micro/hobby business.