Interview: Renaissance man by Tom Ryan (The Age Australia)

So who is Colin Firth when he's not busy being Colin Firth? He says he is certainly not, in real life, anything like the put-upon men he's presented to the world in films such as The English Patient, Shakespeare in Love, Londinium (screened here on cable TV as Four Play), Love Actually, Girl with a Pearl Earring, not to mention Pride and Prejudice.
"None of them are me as I see myself," he declares, "although they probably all are representative of me to some extent. I think they have to be for any actor playing any role. For it to be convincing, it's got to come from somewhere that's you. The question is about realigning the relevant parts of yourself.
"You always have to find something about a character that you like. You can be playing the most despicable human being, but if you pronounce them despicable then you won't be able to make it real.".....more

Interview:"Colin Firth" by Carlo Cavagna (Aboutfilm.com)

And then I tend to pick [something] a little too close to the top of the pile and go for it. Sometimes it's about a relationship. You can think, “Nah, it's not really what I want to do next,” and then you find you're working with the producer of that thing, and he's a wonderful guy, and the director's irresistible, and it's going to be great, and your friends are all in it, and it shoots down the road, and why not, and it's over by April, you know? Sometimes it's apparently frivolous as that, to get you involved. Sometimes you're in before you realize it, with these things. They tend to have a life of their own....more