One great tip I have for selling laptops - make sure that you keep ALL the stuff found in the shipped laptop package when you first bought. You see, a buyer would certainly pay a bit more if the laptop has its original box, manuals, software, cables, etc. So make an effort to keep the original stuff with you - so when you finally sell your laptop, you have some good original stuff and 'extras' to offer the buyer.
 

Always keep all your laptop stuff after you buy it

One of the most important things to do when selling your laptop is to monitor the auction's close. In fact, this does not just apply to laptops, it applies to the sale of any kind of item you have.

Monitor the close of your auction carefully
 

The great majority of bids come in only within the last few minutes of an auction. What some scammers might do is to hijack an eBay user ID, then bid up the laptop as the auction is ending. You have to monitor your bidders towards the auction's close. Those with poor feedback scores or who have not been active in eBay for more than a year are very suspicious indeed.

Some of you may live and breathe by PayPal when you sell your laptop on eBay. Now, PayPal is owned by eBay - and they offer a Seller Protection Policy (covering the selling for up to US$5000 per year on any transaction PayPal deems fraudulent. However, there is some fine print you need to take note of - PayPal only provides cover is the transaction meets some specific criteria (e.g. must be shipped to an 'eligible' address, proof of signature by recipient needed for sale items US$250 and above).

One website that is very useful in selling your laptop on eBay is Escrow.com. What does it do? Well, Escrow.com is a third party that collects, holds and disburses funds according to buyer and seller instructions. These guys are licensed and regulated, and serve to protect both buyers and sellers. They act like a 'judge' in any transaction and ensure that all flows smoothly and fairly.

One lesson I learnt in my eBay adventures (not just with laptops but other sale items) is to hold on a bit before shipping. Do not - repeat - do not ship your laptop to the buyer until at least one business day after a PayPal payment has been made into your account or a money order has cleared your bank. You don't want to send off the laptop only to discover the payment was fraudulent.
 

Ensure your payment is in before you ship that laptop

Here's an important one - do your communication via eBay. eBay has its own built-in communications system and you should fully make use of it. By keeping transactions and communication within eBay, you have a solid and traceable record that will help investigations is you get scammed.

Many people forget to do this after selling their laptop. Please, please please - remove all your personal information, credit card numbers, love notes and passwords from that hard drive on your laptop. There's a good video on 'How to Completely Erase a Hard Drive' out in the Internet that you should definitely watch.