*Look for similar bikes for sale and use that to help you set a realistic price. If you spent £1000 on it but they are selling for £300 on eBay, you should be selling it for about £270 here (saving eBay fees).
*If the price is unrealistically high people will move on and you end up with a trail of "bump"s and price drops. If you keep dropping the price then even if people are interested they know that they should wait another month for the next price drop.
*Indicate "ono", even if you don't want to hear about "nearest offers" don't put people off by refusing to listen (and if it's the only option you have you may reconsider).
*Extras (mudguards, dyno lights, etc) won't realistically affect the price, but may help make the sale. If you have a hub dynamo consider making a price for the bike with a regular wheel, but offer the hub wheel as an optional extra.
*Conversely the buyer may not want your £100 saddle or pedals, so selling without saddle or pedals is quite common/expected.