Excellent reply Wayne. It is exactly what I wanted for this thread.
I would guess that the higher the quality/value of the plane that is being offered for sale, the greater the benefit would be to get some professional quality photos taken of your plane.
If I were to decide to sell my plane, here is what I have have learned so far...
1. Clean it really really good.

2. Get all of my documents in order, and scan the documents that are pertinent for the sale to my computer.
3. Get some great quality and detailed photos of my plane.
4. Burn the information to CDs for mailing to serious buyers.
5. Develop a website that you can link to ads, with lots of detailed pictures and information.
6. Browse different trade publications to get a fair market value of my plane. If you really can't see yourself selling, don't waste buyers time with seller's remorse.
7. Take any item you are not including with the sale of the plane, out of view of any buyers. Once you have your cash in hand you can offer that stuff on the cheap. If you don't, they will want it included in your price.
8. Mention that you are selling your plane to those in your local area first. This may save you a lot of time and money, since the buyer may be at your airport.
9. Place an ad in any and all publications, and include a price that you can come down a little on, and include lots of pictures. Link a website of your plane in the ad.
10. When the ads come out, make sure they are correct. A digit off on a phone number can be the answer to why no one is calling.
11. Have any agreements in writing, and use an escrow service such as AOPA.
12. In your ad and when you talk to buyers, don't make your plane sound like it is better than it is. I always feel better about an item I go see, and it looks better than what was described by the seller.
What else am I missing?