While devising our performance, we used Mike Leigh's techniques.
We didn't go to quite the extremes of spending months discovering every little bit of detail about our characters, however we did do a week or two on finding out a bit about our characters and creating a history for each of them.
I find that by using Mike Leigh's technique helps me a lot because it helped us establish our relationships with the other characters we were working with.

Mike Leigh's technique

Mike Leigh's technique is him basically getting a load of actors together and spending months creating a history for each character by making them improvise it out.
By doing this he's giving the actors a greater understanding about their characters and it makes it easier for them to then act their character emotions and feelings etc.


Why I think this technique is effective

I think this technique is really unusual, however I think it's incredibly clever and well thought, it helps actors get right underneath the skin and into the core of the character they're trying to portray and it makes them truly feel what their character feels.
It's really good for when you're devising your impro piece because you know how your character would react to most things, so therefore you won't be talking rubbish while improvising as you'll have a clear idea about what your character would say to certain things as you would know their history.