There are many widely used best practises or techniques for Business Process Modelling namely - BPMN (flow objects, connecting objects, artifacts & swin lanes), UML diagrams, Flowcharts, Yourdon' DFD, Functional Flow Block diagram etc. However, all of these techniques requires a pre-requisite understanding of their respective notations and symbols. Therefore, its quite often that models created using these technique looks good from an official sign-off or deliverables perspective but they hardly solve the purpose against which they were adopted in first place.
In addition to this, potential of misunderstanding or miscommunication, organizational standards, and contractual or regulatory obligations are also the factors to be considered in selection & adoption of right technique. As a Management Consultant, I help enterprises to choose and adopt to the right technique considering the given context of an enterprise.