There's quite a bit of advice out there about how to start your next web project. It mostly leans towards "the lean startup methodology". Throw up a landing page and spend $$ on ads and drive traffic to it to see if you get some sign ups is the gist of it for us. I've never actually tried it, but it sounds expensive, I launch multiple projects, I try to do one a month, if I spent $100 on FB ads for every one I'd be $1200 in the red every year, assuming (rightly) that none of them took off. It may be better if you want to spend $0 on ads to take a different route, probably a better route for a solo founder.
Make stuff for yourself only
I'm not talking about what I'm doing with streaking, I'm talking about make a website or app, but don't even add sign ups or accounts or anything. Just make a tool that you use every day. Especially if it's already been made before. You've heard of NIH? Indie hacking is the exact opposite, you want to re-invent the wheel, don't worry about adding value or making it slightly different, by definition you'll make it slightly different because you won't be copying code or a design or anything.
Make that stuff great
Work out all of the bugs. Make sure you love it, and you love working on it. There's nothing like that initial idea motivation, but that runs out pretty quickly. So make sure you do those two things, you don't want to get a month in and lose motivation because you don't actually use the thing you're making and/or you don't like making it, it has to be both. Do whatever it takes, use that new framework, use your favorite language, use that tried and true language or framework or whatever, just make sure you love the thing and you love the process
Spread the word
This part is usually the hardest, but now it'll be easy. The goal here is to document your process in painstaking detail. Don't tweet every line of code, but definitely live stream new features or at the very least announce them. Also try to work on a small feature or a bug every day and announce it to the world, via blog posts or a screencast or a podcast or something, anything. Don't be discouraged by the zeros showing up of people reading/watching your stuff. The only thing that matters is that you're enjoying what you're making and you're using it every day. That's it. Things are just that simple.