When developing a WBS, the following basic principles should be followed:
● Every WBS element represents one intangible or tangible deliverable. Intangible items include information/communication, training, administration, procurement and process management. Tangible elements are like wall, machinery, house, painting, a book, electrical/civil works, etc.
● Deliverables are distinct and unique.
● Deliverables include both interim and final deliverables that are required to create the final desired results.
● All important reporting processes such as weekly/monthly reports, review meetings, test reports are included in WBS.
● Every project deliverables should so unique, ensuring no duplication in the outcomes of the project or end-products.
● Accountability for each work package should be assigned to a one team member or a subcontractor. In case, this seem impossible, reconsider whether or not
the work package can be further decomposed.
● Every element in WBS representing externally committed or subcontracted deliverables should directly correspond to associating elements in the subcontractor’s WBS.
● Deliverables are logically decomposed to the level that represents how they will be managed and produced.
● All WBS elements should be compatible with company's and accounting structures.
Also read: Guidelines for organizing WBS elements into the WBS hierarchy
Reference: Practice Standard for Work Breakdown Structures