Start from a diagram that is already right

A ready-made UML class diagram: customer, order, order line, product and a payment method interface with two realizations. Rename the classes and the structure is already right.

A ready-made UML sequence diagram: a request that authenticates, branches on the result and replies. Activations, reply arrows and an alt fragment are all in place.

A ready-made UML use case diagram: customer and administrator actors, a system boundary, and four use cases wired with include and extend. Rename the ovals and the scope is stated.

A ready-made UML 2.5.1 component diagram: storefront, order service, order store and payment adapter, wired through named interfaces rather than straight to each other.

A ready-made entity-relationship diagram: customer, order, order line, product, category and the junction entity between them, with keys and cardinality already correct.

Entity-relationship diagram

A ready-made BPMN 2.0 process: start and end events, two lanes, an exclusive gateway with both branches drawn, and a message flow to a collapsed customer pool.

Business process diagram

A ready-made ArchiMate layered view: a business process served by an application service, itself served by a technology service, in the spec's own layer colours.

Layered view

A ready-made cloud architecture diagram: browser, CDN, load balancer, application runtime, managed database and cache, inside a region boundary, with protocols and ports on every path.

Deployment diagram