What are the most costly mistakes you've made early on?
You can often read about folks focusing on unimportant stuff, like spending days perfecting the logo and choosing the name before even doing any substantial work.
What are the costliest mistakes you have made?
What are some mistakes most people would think are fatal, but turned out more or less easy to undo for you? (e.g. badly set price points)
I've been trying to think of something profound, but really my biggest mistakes have just been wasting time building the wrong thing. I'm a developer so I feel like I'm making progress when I'm writing code.
Really, though, businesses don't run on code. They run on providing something of value to someone who will pay for it. The code is just the how.
Sometimes I've spent months building a product people just didn't want. Sometimes I've spent months building the wrong piece of a product that people did want -- just not that piece (or prioritized wrongly).
There really are no end to the mistakes you will make, though. I've been indie hacking for almost 10 years and though I've seen some "success" (read: sales), I certainly have not gotten ahead or been free to quit my day job.
I think the most important lesson I'm taking away from my mistakes is to be thoughtful about the direction I'm going in. I have to force myself to take off the developer hat and put on the product owner hat. What does the customer want? What will they pay for? What is the quickest way to get to revenue? These are thoughts that the developer really doesn't think about. He's too occupied thinking about technical challenges and system architecture. He'll emerge after months of developing something any other developer would tip their hat at, only to find that he's really no nearer to his goal of revenue than before.
TLDR; put in the effort to determine what you should be doing with your time.