Most small operations know their total for the year and nothing about which work produced it. The difference between those two facts is usually a whole category of job.
The first meeting with a preparer is a two way interview and most people treat it as an application. The questions below take twenty minutes and settle it.
Federal tax gets the attention and state and local obligations produce most of the surprises, because there is no single rulebook and nobody sends you one.
A large company's standard agreement is written to protect the large company. Most of it is negotiable, and knowing which parts to push on is the skill.