It is normal practice for buyers to offer 5-10% less than the advertised asking price so don't be surprised if initial offers are a little low.
There is no need to accept or reject an offer straightaway, it is perfectly normal to think things over for a day or two.
It is a good idea to find out from your estate agent the buyers position first before making any decisions as there are other important factors to keep in mind when deciding who to sell your house to:-
What is the financial position of the potential buyer?
Do they have to sell a home in order to move?
Are they a cash buyer?
Do they have a motgage approved in principle?
What are your buyer's timescales for moving?
Do they need to move quickly?
Are they part of a chain?
Are they flexible on a move date?
Also consider your own postition
Do you have to move quickly in order to secure your next house? If so then you may be more interested in accepting an offer from buyers who are not part of a chain.
If you are in no hurry to move, then you could hold out for a higher offer.
A buyer who is not part of a chain and who already has a mortgage approved is a more favourable purchaser than someone who needs to sell their own home in order to fund the purchase, and who hasn't yet got a mortgage approved.
Accepting the offer.
If you do accept an offer it is usually @subject to survey@ which means as long as the survey doesn't throw up any surprises, the buyer will keep their offer.
The accepted offer is not legally binding until contracts are exchanged.