Questionnaire Design

I think it depends on what you want to do with the responses, in terms of quantitatively statistical validation of what you already assume or qualitative inquiry beyond that. For the former, i remain silent :o) for some essentials regarding the latter, eg 'Qualitative Sozialforschung' / 'Qualitative Forschung', see Flick, U. / Flick, U. et al, respectively (rororo paperbacks). Also the grounded theory stuff directly from strauss, a. & glaser, b. et al is interesting but may not immediately be 'hands-on'.