I’ve spent some time trying to find one definitive place for burglary prevention advice – the best I’ve found so far is this website http://thecrimepreventionwebsite.com/ and its Home Security Survey.
You can also ask your Police Safer Neighbourhood Team for a free crime prevention visit but they wont give you such a comprehensive survey of your home.
Locally we still have free SeletaDNA Property marking kits. The Police promote Smartwater but it has a shelf life so far from ideal.
Banham locks and alarms have a good reputation http://www.banham.co.uk/ I love the fact we just have one key for all external locks both the yale equivalent and deadlocks. You need both on front and rear door. Classic is rear door forced entry.
Also ensure hinge bolts, Manchester and London bars to protect the door frame week points where the hinges and locks are – easy DIY jobs that even I’ve done.
Double or even triple glazing is best. In SE22 we have real issue of single pane sash windows being forced or smashed. If you need to keep single glazing sash then good window locks and a laminate or plastic coating can be added so that the pane can’t be smashed easily.
If you have any side or rear access make sure it is gated and locked.
The Met Police also have a book of scams that is a useful read – http://www.met.police.uk/docs/little_book_scam.pdf