I'm an internationalisation expert, digital marketing mentor and productivity addict. I help small businesses promote their foreign language sites through SEO, Paid Search, social media and e-mail marketing. I can also help companies optimise their employees' productivity and improve their operations.
I'm in the same position at the moment and found this calculator quite helpful https://www.seedrs.com/learn/guides/startup-valuation-calculator
Hope this helps to get you started.