Commissioning a portrait for Christmas, a birthday or other big event is a great idea...except for the fact that this usually means a lack of good photographic references and a too-short time frame. Often, because of the surprise element, I don't have the opportunity to photograph the subject, spend time with them in their surroundings and most importantly, find out what preferences they may have. The information I get in a meeting is invaluable to producing a successful portrait.
My solution to this is to offer customized certificates with a special message to the recipient, samples of my work, and a detailed account of what the portrait includes. The certificates are available for $25, but are deducted from the cost of the portrait. I offer both pet portrait and people portrait certificates in standard sizes that are easy to frame.
Before issuing a certificate, I make sure that the giver understands what the precedure of the portrait will entail and a cost agreement between the giver and myself (half to be paid when the portrait is started and the balance due with the delivery of the portrait). As you can see, the giver of the portrait is very much involved throughout the entire process.
For long distant clients or for posthumous portraits, I walk the client through a step-by-step process of photographing or selecting existing reference material. This is not as helpful as a face-to-face meeting, but can be a reasonable alternative.