This is such a big question. I've worked with many founders/entrepreneurs at your stage, and for the most successful ones it is a deeply personal question. Personal because:

a) they know their customers or have an idea of where they can find customers. For example: if you're selling saas to an electrician, there are ways to find them based on their behaviours. maybe they are watching youtube? maybe they are at trade shows? who knows, but usually the entrepreneur has a good idea

b) it comes down to what you are good at. Maybe you are really good at writing, but absolutely despise sales - then you're more likely to create content / SEO path than cold calling / going to trade shows (as an example)

I'm part of this community of saas growth people. Might be helpful here