I don't often write Sam either very much, except as a minor supporting character. And so I only have one piece of advice: I see a number of writers dumb his speech down too much (in my opinion). For example, using "in'" instead of "ing" for his speech---it isn't that way in the books. Yes, he speaks with more idioms and "aint's" and slang than the other hobbits, but still, he's a bit of a cry from Ellie Mae Clampett, which is how I see him written sometimes. So... that's my two cents. :)