What seller need from the Buyer to get started?
For the deliverable:
Preliminary requirements are all existing documents and communication around commercials and subject matter or technical information.
First round of discussion explaining business and objectives, existing solutions to current challenges, the area of improvement or area where client needs support, and expected delivery and format of delivery.
Budget:
Payment model whether it be per hour or task, retainer, project specific, FTE?
Engagement type:
Project, short term, long term, seasonal?
Tools:
Access to tools if the work requires.
Lastly and very important: Professionalism, politeness, courtesy, transparency.