A cloud is a visible mass of droplets of water or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. (c) wikipedia.
The problem is to find a startup since almost all of them prefer to work in stealth mode and second is to convince them that you're right guy. So for example, I realy would like to work (even with $0 salary) on interesting project/startup, but all attempts to find something literally failed. Just for the record, I was looking for Python/C++/Java/Erlang (one or all languages) startups.
What type of attempts? Have you tried going to events, meetups, and (un)conferences etc.? It is a great way to start. Meet people, learn what they do, let them learn about you. Once people see you at several events over time, and you get a chance to bond with one another, they are more inclined to take you on, especially if you can demonstrate skills/portfolio (even if, for example, it is just your own personal projects on a blog).
If you are in London, email me and I'll see what I can do to help. There are several startups here that can always use extra hands.