How did you acquire your first 10 users/customers?

First 10 was friends and family (B2C product). First 100-1,000 is much harder now than it was 10 years ago. 10 years ago was a "if you build it, they will come" type landscape, but now there's a lot more noise for B2C products.

I believe you need a marketing strategy day 1. Facebook Ads (as much as I hate to say it) seem to be the easiest and cheapest way to target and find the first batch of users.

Organic search. It might seem counter-intuitive, but think about how you reach customers and then tailor a product to them.

Creating a product or service and then wondering how to market it is a problem.

Ask yourself why you created the product? If it is because you thought it was personally interesting, that's fine. However thinking about the consumer, the problems he faces and how he searches for solutions avoids this problem.