I would like to add to the responses here because I have been considering a new method of providing proofs for my clients as well. For the last two years I have been using online proofing exclusively. This has been very easy and quite handy to provide my clients with a quick and easy method of viewing the results of their sessions.
However, I have had almost no orders from this. Now, this may be a direct result of the quality of my work or a commentary on the price of my proofs or possibly directly related to the ability of the client to actually "buy."
I have been considering advice that I have recieved from more than one professional wedding photographer that suggests never to use online proofing because your client feel no motivation to purchase and since they can view online, they can share with family and friends as well.
By incorporating personal presentation you can offer proof books or dvd slideshows that encourage ordering from directly from you with the added motivation of discounts available if ordered within a specific time frame. I thought to provide a deep discount on orders placed during the initial viewing with the goal of obtaining orders while the emotion of the moment is the motivating factor. Then I might consider another level of discount on orders received within 30 days wherein prices would revert to full studio price.
I have discovered that I can produce a dvd slideshow from within my Mac using iDVD with very little trouble. I have also tested an application called PhotoJunction for producing wedding albums that produces a Quicktime video of any album or book that I design. This is an amazing application that is half the price of most other application used to produce press books or albums. I havn't purchased it yet, but the trial version works for a specified period and I found PhotoJunction very easy to use once you complete the set up. The slide shows are very nice quality and can be emailed or posted online.
So, I'm considering only using proof books and dvds as my method of proofing to allow greater control over my sales.
The second part of your question asked about how much post processing is completed before proofing and I don't work on anything that I haven't sold. I say this but actually I sort all shots before preparing proofs. All rejects get deleted permanently. I don't want anyone seeing the bad stuff and I usually have enough good stuff to using for anything else I need like backgrounds etc.
I hope this helps and I will be watching for others comments here as well.
www.billzaspel.com