The sample used (e.g. who were they)
Sampling process (e.g. volunteer sampling)
The main method used (e.g. experimental, observational, self-reports)
Any other methods used for data collection (e.g. self-report, technical equipment)
The experimental design used (e.g. independent measures)
Other techniques used(e.g. coding scheme, questions)
The type of data (quantitative vs qualitative) statistical analysis, objective, subjective etc