DESCRIBE IT
So you've used MacTracker to identify precisely which model Mac you  have. You've even learned that it's officially called, for instance, a PowerMac G4 (QuickSilver 2002ED) and has an 867Mhz processor in it. In your advertisement you should include this information. Here's a list of other information you should include:

• the specific model of Macintosh
• the amount of RAM installed in it
• which optical drive the machine has (CD-ROM, CD-RW, Superdrive?)
• which graphics card is installed and how much VRAM it has
• whether the machine is as Apple shipped it or whether it's been upgraded
• whether there's any obvious damage or scratches/markings
• whether there are any known physical malfunctions (CD drive doesn't open, for instance)
• which version of the operating system is installed (if any).
  

Most of this information is available from the Apple System Profiler. It's also listed in MacTracker's database. MacTracker is useful in cases where the Mac doesn't have a bootable operating system installed (and so therefore you can't run Apple System Profiler). If the Mac doesn't have an OS installed or won't boot, be sure to include this in your listing.

Take a good picture of it! You wouldn't believe how much a good picture of the product helps sell it. Try to use a picture of the actual machine rather than a product shot from when the machine was released. The difference is obvious to most buyers and having an authentic picture increases the legitimacy of your listing.

PRICE IT
So now you have to make a determination on how much this Mac might be worth. I've seen some wildly crazy listings with sellers asking for overvalued prices and also listings where the seller has no idea what he has in front of him and is asking too little. A fair asking price is an important detail, if only so you don't get those crazy emails from people insulting you for your asking price, but also so you don't get ripped off. There are several tools I use to determine the approximate value of a used Mac. The first is to search eBay's completed auctions listings for similar or identical models. You will need an eBay ID to do this, but it's worth signing up for one if only for this feature. There's a very good chance there will be several if not many completed auctions for an item similar or identical to yours. Scanning the final sale prices on the listings will give you a good idea how much your used Mac is going for and will let you estimate a market-value asking price. While not as accurate, Craigslist listings will give you another indicator of price, demand, and even whether there's a glut of your model being sold. For some reason, a lot of people selling Macs on Craigslist overvalue what they're selling, but it's still a great place to help gauge the market for your used Mac. Other places to look are:  UsedMac.ca, MacSwap.org, SecondhandMac.com, and Macofalltrades.com.

SELL IT
Sell it as soon as you can! The longer that Mac sits unused, the lower its price will be when you finally sell it. I've personally made that mistake several times, sitting on a used Mac for months (or even years) before finally getting around to listing it. It's not a pleasant realization that your procrastination lost you hundreds or thousands of dollars.

Any of the above sites I've listed is a great place to sell your used Mac, but the ones I've had the best luck with are eBay (because it's audience is enormous) and Craigslist, because I can target my local community. It's often much easier to sell a Mac locally than it is to ship it to a person you've never met. What you use will depend on where you live and whether you want to try to get the best dollar for your used Mac, or whether you're just looking to unload it quickly.

A few tips about timing. If you're using an auction site like eBay, consider timing your auction to end on the weekend. eBay's audience is larger on the weekend than it is during mid-week. Also, selling near the Christmas buying season is a great idea becuase people are always looking for deals. Also, please list your Mac with the proper and accepted spelling:  it's "Macintosh" or "Mac". It is not "MacIntosh" or "MAC". You might think this is a minor point, but trust me that you do not want to look like a seller who doesn't seem to know the Macintosh market. This mistake is a surefire way to identify which sellers know the Mac marketplace and those who don't.

RELEASE IT
Congratulations, you've located a buyer. If this Mac was your personal machine, you really should consider wiping its internal hard disk and installing the operating system fresh from the CD's or DVD's that came with it. This will ensure that you're not giving away a machine with personal and confidential information on the Mac. It will also ensure that you're not selling the computer with software installed on it that belongs to you.

Clean the computer. We had a tip a few weeks ago about excellent ways to clean your Mac. I consider it distasteful to buy a used Mac and find it filthy. Delivering a clean computer to your seller will ensure you get excellent feedback. If you are shipping your used Mac, be sure to pack it properly. If you have the original shipping boxes, use them. But you can also use a professional packing service like Mailboxes, Etc. Some post offices have packing materials for sale as well as FedEx and UPS stores.

Identify it. Describe it. Price it. Sell it. Release it. Good luck selling your used Mac.

Readers, please let us  know if you have any additional tips for selling used Macs.