When you sell something online, there are some things you can advantageously include in your ad. There are some things that you may still be asked about that you can include in the ad and thus get your items sold faster.

HBO (Highest Bid Over) or minimum price.
Price is incl. freight or buyer pays freight.
Pictures – preferably with as many details as possible.
Location – where is the item located?
Is it possible to see the item physically, possibly pick up and thus save freight?
Receipt and any remaining warranty?

Description is important

If it’s IT / computer equipment, describe the item as best as possible, with as many details as possible. With specs / specifications and preferably also with model number.
Specs can e.g. be things like:
CPU (Processor), Intel or AMD? Number of GHz? Number of cores? Model type and number?
PSU (power supply), Model type and number? If it is ATX, what type, connections  and max watts.
GPU / graphics card, Model type and number? On board? Dedicated RAM? Connections – e.g. VGA / DVI / DisplayPort / HDMI? Max resolution?
RAM, Model type and number? Number of available slots on the motherboard?
HDD (hard disk), Model type and number? RPM / rotational speed? Or SSD?

If it is a laptop, then the screen size and resolution is also important to mention. You can describe which ports it has. Also like functions such as webcam, fingerprint reader, etc. Remaining battery time at full charge can also be nice to be informed.

What is included in the sale? If, for example, is a mouse included, so remember to write that, as the buyer might just be in need of a mouse. If, for example, follows a Windows license and installation media (e.g. DVD) with, so remember to write the version number, type and whether it is 32 or 64 bit.

Consider the specs and age when you set the price fairly, and you should be able to sell your things.