Verify the basics.
Start with the people, the business, and the records behind the proposal. Check that ownership, responsibilities, and claims can be explained and supported. A confident pitch is a starting point for a conversation; it is not the whole review.
Make the responsibilities clear.
Put the proposed work, use of funds, deliverables, and reporting expectations into clear written terms. Each party should understand what they are responsible for and what happens if the plan changes. Good documentation gives everyone something concrete to work from.
Give the decision enough time.
Pressure to act quickly can make important details easier to miss. Ask questions, review the risks, and bring in appropriate independent expertise when the commitment calls for it. A sound working relationship should leave room for that process.