If you are going to stay out late at night the only way back to where you are staying will be a night bus or an unlicenced taxi (black cabs are almost impossible to find after 2am). These are usually fine but haggle for the best price and don't travel alone if you are a woman.
The best advice I can give here is never take an un liscensed taxi,,only use black cabs that are the old shape taxis,,,they are safe and registered with the Governent. The other basic things apply ,,,don't carry large amounts of cash on you take some travellers cheques and never carry your wallet in your back pocket. Keep all handbags tightly held and never ,,, I repeat never girls hang your bag on the back of your chair by it's strap when you are eating in any Restaurant,,, for sure it won't be there when you turn around to pay the cheque..... ''it's life guys''
Upon arriving at Heathrow airport. Be wary of private taxi touts. They ask for an arm and a leg. Either take the black London cab (they may cost more but all fares are metered and you are entering the vehicle that has been recognized as a taxi as oppose to the cars of total strangers.)
Watch out for non liscensed taxis that are around late at night, especially at clubs. There have been some problems with them, and if in an accident, they have no insurance to cover you, as in a black cab. Its more difficult, but about the same price,so take black cabs late at night.
Watch out for Taxis!
Be careful when using taxis in London. If arriving at a railway station (and this will almost certainly apply to other places) be sure to get your cab at the taxi rank. Do not accept lifts from people who approach you on the platforms (or other places) and offer to take you to your destination. Yo will be charged well over the top for the journey, and it may not be safe, either! Use the properly regulated London taxis.
Stay away from unlicensed taxis. London black cabs are legendary and reliable. They are not all black anymore but have a distinctive style reminiscent of cars from the 50's. There are also hundreds off other people running around offering rides . STAY AWAY, you are far better off walking in a windy rain than taking a ride from one of these crooks. Other than that, central London is a very safe place. Be mindfull of pick-pockets and keep track of your belongings in public places. Mostly common sense stuff.
During the Summer especially, be wary that the volume of tourists rises dramatically. You will find that the London Underground System ('The Tube') will cause your journey time to be protracted. Also, be wary of 'mini-cabs', who are unlicensed taxis using private cars - better stick to the traditional Black Taxis - besides, the drivers are very knowledgeable, and will be able to suggest places to go at reasonable cost.
Never ever take Black cab, unless it is really necessary. It could cost you fortune. Black cabs are safe but really expensive.