Forgot to add
Just some basic safety precautions that we use,
Lock your valuables away before a viewing.
Will you be happy giving out your phone number and e-mail address to people you don't know? Maybe get a cheap PAYG phone.
Have a get-out clause in case some weirdo turns up.
Can you verify the viewers identity beforehand?
Have an escape plan if you feel uncomfortable part way through the viewing.
Let someone know that you have a viewing, who it is and when you will be finished, get them to call you if you haven't called them by a certain time, and to call the police / get straight round if you haven't called them by a certain time.
Unlock all the outside doors so you can get out of the house in a hurry if you need to - think about how you will get you and your child out if they are in a different room and things turn a bit nasty.
Close all internal doors and open them one by one, that way the viewer isn't to know that there isn't someone else in the house.
Let them go into a room first and follow, never let them get in between you and the door.
If there is more than one viewer, how are you going to stop them wandering off separately?