With a gain of rich seven years experience in interior/ lighting design & 3d visualization & since I had a hidden reason for establishing this freelance activity, which is "to represent the genuine definition of Interior design in my country & for my people," since then, I've created a service rule to make tasks organized & easy for the client, I call it the 3x4 Service. 
So, it's a rule of 3 phases, each phase contains 4 tasks to be accomplished. Each phase of work is an independent service, and the client is free to terminate our given service at any end of a phase.
                                         3x4 Services

     Conceptual Design              Designing Works               Implementation

1- Sketches & prototypes for the interior spaces of the project (for new projects or refurbishments).
2- Facilities programming and space planning.
3- Sit with the customer on adding the personal taste.
4- Draw the conceptual sketches & plans & determine the focal points. 

1- Contain the architectural drawings & plans
2- Do the shop drawings & details within the original architectural plans.
3- 3d visualization and make models for the final design.
4- Feasibility studies

1- Make a sample board of materials & finishes.
2- Specifications study & BOQ.
3- Procurement management.
4- Installation.