One of the objectives of Circles4EU was the collection of best practices in COSA implementation. This report on best practices is one of the deliverables in workstream 3 of the project Circles4EU.In this project, COSA pilots were started in Latvia, Spain and Bulgaria, while project partners in the UK, The Netherlands and Belgium had already fully operational projects. As a new or an experienced COSA provider or facilitator, one has probably encountered situations that were different from standard COSA procedures or that needed a special solution. Maybe some of the solutions found are useful to address problems that occur also in other countries; or maybe they have raised questions, and one would like to get some opinions or advice from other project partners.