I don't have any good place to do my writing work. I've just had to deal with it.
Usually I play music on head phones. It makes it easier to switch between 'work' and 'non-work' even when there are only small periods of work that I am able to have. My brain has gotten used to the environment of headphones being the work environment. I am able to get stuff done without as much time used up for settling down and getting back into it every time I get interrupted.
Also, when I am using headphones, I can't hear as well, and anybody who wants me actually has to come and get me; they do that less often than when they can just call me from another room; a helpful psychological behavior I guess.
Some people don't like listening to music while they are working, and I would actually prefer not to, but it is necessary, and works for me. I usually listen to the same album for days, maybe a month, before getting tired of it so that I've got to switch it out for another one. Usually the music I listen to does not have anything to do with the book I'm writing: it is just, content that has the right levels of stuff (I don't know what to call it o_0) so that it does not disturb my work. It actually ends up being different with different books, though, anyway. I tried listening to jazz for the book I'm working on right now, and it messed everything up, but it would be perfect for my next book that I'm planning.
The biggest interruption for me, aside from house chores, is my littlest brother asking me to play with him. So I've also had to begin to say no often. He's usually very kind about it. I play with him when I can when I'm not working, so it makes up in the long run.

He asks me if we can go have a picnic, and I say, 'No, I'm sorry, I must work right now', so then he says, 'Alright, yes you may work.' **grins** And sometimes he just sticks around and does chin ups hanging from my elbow and makes his stuffed animal slide down my back or something.. which makes things a little more difficult, but at least I can work.