I'm a post doc for a nationwide field trial testing the effects of a math curriculum revised based on cognitive science principles. As part of the fidelity measures, I, along with my colleagues, interviewed teachers using the revised curriculum. Because the teachers' experiences and opinions with the revised curriculum are very important, I would like to analyze these interviews. However, I have never done qualitative research before! Could someone suggest a handbook or guidelines that would give me a good starting point? Or a stellar researcher in that field I could look into?