As a consulting practice, I generally:
a) FREE: The first one to 1 1/2 hour meeting to understand the needs of the business owner. Generally a question and answer meeting and I ask most of the questions.
b) I will quote either an hourly rate and bill accordingly with net 15 day terms or
c) prepare a project proposal with scope of work and goals and require a retainer and interim billing with 15 day terms
d) a company check is sufficient