Proposals
Writing proposals that define deliverables tightly enough that everyone knows what is and is not included.
How to define deliverables so a client cannot expand them
A deliverable written as a noun has no edges. Give each one a count and an acceptance test, and there is nothing left for a client to widen.
How to charge for extra revision rounds
A revision round becomes billable the moment it stops matching the proposal. Define a round properly, then price the extra ones from what delivering one costs.