What kind of company are you trying to found? For this answer I'll assume you're a software developer starting a B2B SAAS. #1 Product market fit. Skills wise t

What kind of company are you trying to found? For this answer I'll assume you're a software developer starting a B2B SAAS. #1 Product market fit. Skills wise this means you need to talk to customers and understand their problems. Jobs-to-be-done by Tony Ulwick helped me with this. Interviewing customers is super difficult and counter intuitive. #2 Sales and marketing. This is a huge topic, easily as deep and counter intuitive as software. engineering. I found marketing for developers by Justin Jackson helpful as an intro. #3 Now you've worked out what to build, and how to sell it, you can do the easy part. Build the actual product.