I don't work with web design but do freelance (primarily industrial and 3d design) so I'll give my approach as well.
Bearing in mind I have an automatic nda for all work I undertake.
1) Meeting to discuss brief, break down requirements with client while there. Say I'll get a quote out for them by end of next day.
2) go home and work out quote and proposal (in simple/plain english), time frames for meetings if needed etc, send to client via email (passworded pdf) with a phone call follow up to check it's all ok on their end. This states that once agreed any changes may incur additional charges (there's another stage which has this too for me personally).
3) They say yes via email and/or signed contract.
4) Wait on initial payment towards work.
5) I start working on required work.
My work process usually goes something like this.
1) break down of project into sections
2) work out what's needed for each section
3) work on concepts
4) show concepts to client for feedback
5) develop concepts
6) show final concept(s) to client - repeat 3-6 if needed.
7) develop final concept(s) in 3D
8) Show 'clay render' to client if necessary (some clients just leave me to it)
8) apply materials, lighting etc for rendering
9) do smaller low quality render for 'material/colour approval' -
10) show to client - get them to sign off on it - includes a clause that any changes after this point may incur additional charges.
10) render image(s)
11) present to client
12) send final invoice and wait on payment
Rinse and repeat with the next client
