The Doctor Who star is the eleventh actor to take on the role but he told Zap2It that he did not watch his predecessors for inspiration.
"I haven't looked at them for performance notes," he said. "It's my own invention and that's the way I like it. The role is too big to borrow from anybody."
He continued: "The experience is one that I've enjoyed thoroughly. I had no considered ideas of what I should try to do. I just went and did it every day. I had no grand plan. I think it's turned out that he's a bit bonkers. Hopefully the madness of his thoughts will come through as the show continues."
Smith added that he has tried not to compare himself to the previous Doctor David Tennant.
"I'm a different human being, a different soul, a different mind," he explained. "David Tennant and I, we just do it a different way. It's for other people to decide how my Doctor has changed from the previous. I never consciously did anything to be different.
"I just play the role as truthfully as I could in my body and soul and mind."
Doctor Who continues on Saturday at 6.20pm on BBC One and on Saturday at 9/8c on BBC America in the US.