Dean, if you're flogging something then more info is good, so pictures, detailed description of all parts(or a link to the online spec) and an indication of wear and tear and miles done. Have a read of some of the other classifieds ads to get a feel for it.
Pricing is trickier as it can be quite disheartening the size of the gap between what you think it's worth and what people will even consider. Even with brand new unused items I've never lost less than 20% and somewhere between 30-50% is normal. This is also based on current prices, doesn't matter if something cost me £50, if it's available on sale now at £30 then the £30 is the price I have to work from.