This is usually the most time consuming part of the process, you should arm yourself with an A to Z and prepare for a few long days of wandering around the
streets. You are looking for the tell tale signs that a property is
unoccupied.
There are thousands of empty properties, some of which are more obvious than others. The most obvious are the ones with steel doors, which can be hard to get through, but boards, or a general abandoned look are a good sign. Look around and ask around. Local squatters' groups have lists of empty properties, but rely on everyone to keep them up to date. Make sure the place is actually empty before doing anything.
If you are looking at a house, it is best to squat one that has been empty for at least two or three months i.e. a little bit run down. You will probably be able to live there longer.
Accept you will not find an unoccupied mansion, it has happened but your are less than likely to find an owner who will put up with squatters if has a chance of selling the property. You are most likely to find an empty council property but if you have a large group of people it is possible to squat unused truebraries, pubs and office buildings.
A for sale sign means just that, the owner of the property is attempting to sell it. You can contact the estate agent and find out how long the property has been on the market, but my advice is to stay well away.
Citex is your best sign of a good property to squat, it is mainly used by the council to protect long term unoccupied properties. If the building has citex on the ground floor BUT none on the second this should be your prime target. If it has citex on both levels it usually means the property has been condemned... but check round the back if possible just to make sure.