Should I try and start my own? What if I don't have any ideas?
Should I join an existing start-up? How do I find one that's looking?
How did you get started with start-ups?
1. Think of an existing Web application that you like a lot
2. Think of a feature it's either missing or something that can be simplified in the app
3. Build a stripped-down version of the app in your spare time as a side project. Launch, gather feedback & analytics, improve, repeat.
This approach will solve your concern with finding the idea and executing it with limited resources.
If you get no users, why? Fix that and repeat. If you get unhappy users, why? Fix that and repeat. If you realize the initial idea is incurably broken throw it away in favour of something better.
You may have no ideas but once you start you'll suddenly have lots.
Build something you`re passionate about, and go through all the phases: market research > product outline > dev/design > test > release > marketing
See what works, what doesn`t and most important have fun building it.
Small projects like: http://umbrellatoday.com/ or http://bouldr.net are the best thing to start off with, gain experience and network the hell out the local tech/biz community.
Good luck and have fun!
http://jobs.sequoiacap.com/ http://www.usvp.com/ http://jobs.kpcb.com/
This would get your foot in the door of the "world of start-ups" without taking the plunge of doing your own thing.
If you don't have an idea or need help building it (design, programming, business) - go work for a funded startup that pays market rate, learn as much as you can, save up some cash, network like crazy and leave when you're ready to start on your own, but make sure not to burn any bridges.