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.