I've started and abandoned maybe seven side projects in five years. The pattern was always the same: I'd get excited, spend 6-8 weeks building something, show it to a few people, and discover they didn't actually want it. Or they liked it but wouldn't pay for it.
The one that stuck -- a Notion template pack I now sell for $29 -- I validated in about 10 days without writing a line of code.
Here's exactly what I did:
Week 1. Manual version. Instead of building the thing, I manually did the thing for 3 strangers from Twitter DMs. They described their problem. I spent 30 minutes each creating what I would have built the tool to output. I charged nothing. I learned: (a) the actual job-to-be-done was different from what I thought, (b) what they found most valuable, (c) how long the manual version took me (useful for understanding if automation even makes sense).
Day 7. The landing page. Built a one-page site on Carrd in a few hours. Single clear problem statement, a mockup image, and a 'join waitlist' form. Put the price on it. No fake countdown timers, no 'beta launching soon' vagueness -- just the actual thing and the actual price.
Days 7-10. Traffic, not cold pitches. Posted in two subreddits where my target user hangs out, one HN thread that was tangentially relevant, and one Slack community. Not 'check out my thing' posts -- I answered existing questions and linked to the landing page once it was relevant. 74 page views in 3 days. 11 waitlist signups. 2 people emailed me asking 'can I pay now.'
That was enough signal. I built a v1 in 3 weeks and sold it to the waitlist first.
The part I got wrong on every previous project: I kept trying to validate interest instead of validating willingness to pay. Those are different things. Someone saying 'this is cool' is worth almost nothing. Someone typing their email into a form on a page that says it will cost them $29 is worth something.