One of the first questions you need to answer: Is this a load-bearing wall? You certainly don't want to demolish a wall only to have your attic and roof come crashing down along with it. We hear that can cause grievous injuries -- and we firmly believe it. Not to mention, you know, the fact that you'll have a roofless domicile at that point, which pretty thoroughly defeats the purpose of having a house in the first place.
If you're still fairly new to interior wall deconstruction, it's a good idea to consult a contractor or structural engineer. He or she will be able to give you an expert opinion regarding which walls can go, and which are integral to keeping a roof over one's head.
Once you know if a wall can be torn, it's time to get started.