Pick the ethnomethodological tool that answers your questions best:
- Interviews and observations (mainly), face to face > phone > online > email. Start with 3 broad questions and then get specific and dig each of them.
- informal interactions ("hanging out")
- participant observation
- focus groups
- collection of artifacts
- content analysis
Ethnomethodology is one approach of ethnography, it is oriented on accounts of people (conversation, text, video), has no theoretical stance and data collection lasts for a few hours rather than a few years. Hence do no say you are doing ethnography if it is only an observational study.
The research topic should be framed to be interesting, not juicy (it is not journalism!). Use the past tense, but do not use metaphors.
Ethnography has quantitative ports but its goal is more about understanding people from their own point of view (and in general, it is hard to define categories for that). Subalterns are those not in the powerful culture. As they are not on the front scene, ethnography is very useful to get their opinion.
Beware of generalization, be conservative. Draw portraits of people, their everyday life and eventual exceptional events. Stop when you can build a solid argument from the data and/or when new participants do not seem to bring any new content. Data analysis has 2 phases:
- take notes
- identify patterns and outliers/exceptions (border-line cases define the border!)