ERP systems projects have been spread widely across many organizations in general and small and medium enterprises (SMEs) in particular. Regrettably, failures were the results for most of the ERP implementations. As a result of that, critical failure and success factors (CFFs & CSFs) have been identified with the help of large number of researches. Accordingly, data quality and user participation were categorized as two of the most critical factors that threaten the success of the ERP projects. In order to raise the success percentage of such projects, a data cleansing methodology and some guidelines for user participation have been proposed.