Sequence Allocation: Is it random? Is it convenience? How were they selected?
Allocation Concealment: Was it blind?
Blinding of Participants/Personnel: Did the participants or person conducting the intervention or collecting the data know who received which intervention?
Blinding of Outcome Assessors: Did those interpreting the data know who received the interventions?
Incomplete Outcome Data: Did they report all participant #s (for characteristics, for interventions, for attrition, for exclusion)?
Selective Reporting of Outcome Data: Did they report both positive and negative data? Did they admit any limitations or problems with their study design? Did they fail to report a part of data about that pertains to their research question?
Other Sources of Bias: Conflicts of interest ($ or affiliations of researchers), if study was localized to one region/state/setting, if diversity was lacking, etc.
If you are unsure of what data would be useful in your summary tables, try finding a systematic review on a similar topic and look at what details they use to summarize their included studies.