When I have picked my travel dates, I visit various on-line travel sites, such as Expedia, Kayak, etc., to find the best deals on flights. However, it is also a good idea to double check the prices against the individual airline web sites, such as American, Virgin and British Airways, because sometimes you can get a better deal if you go to them directly.
By the way you will need a current passport! So make sure you get one in plenty of time before your trip (or renew if it is expiring soon) US citizens do not need a special visa for vacations or business trips in the UK if the visit is for less than six months, (although I heard that the Brits are considering changing this time frame to three months some time in the future.)
Step 1: Flying away!
Step 2: Hotels, relatives and jelly beans...
Step 3: Inform the relatives!
Step 4: Travelling around in England via British Rail
There are a choice of passes depending on how long you are traveling around. These travel passes can only be purchased outside of the U.K. so have to be got ahead of time. They are valid for three months, and if by chance you don't use them you can get your money back, less a small fee. If you are going further into Europe, you can also buy travel passes for travel there also.
Step 5: Explore the mysteries of the London Underground
You can also get special passes to the London underground (the tube)
A map of the underground will come in handy.
By the way, the Underground has some very interesting posters on the walls, although sometimes it's difficult to know what they are advertising!
Step 6: Bus travel is good too!
Don't forget the traffic moves on the left side of the road! Be careful crossing the roads.
Step 7: When in doubt take a taxi
Step 8: Seeing the sights
Of course there are lots of places to visit free of charge, like Tower Bridge, Covent Garden Market and Trafalgar Square. A visit to St. Paul's Cathedral http://www.stpauls.co.uk/page.aspx?theLang=001lngdef&pointerid=169345dwprEOVViTRLd8xXbHBDHGbzge will cost you but it's worth the view from the dome and the ball and cross if you have a head for heights.
The Tower of London is worth visiting to see the crown jewels alone. You will get free admission with your London Pass. http://www.hrp.org.uk/toweroflondon/
I love the the British Museum!
http://www.britishmuseum.org/default.aspx The Great Court alone is well worth a visit!
My favourite museum is the Museum of London located in the City at the Barbican, where you can trace London's history from Roman times to the present day. Also the Lord Mayor's coach is on display here.
The London Eye http://www.londoneye.com/ will cost you but the views are amazing - don't go on a rainy day, as you won't see anything!
Step 9: The terrific Thames!
There are many different tours offered with starting points on the north side of the river, including those at the Tower of London; at a place close to Westminster Bridge and on the Embankment at Charing Cross. Each boat usually has a guide who points out the sights on the river bank as you float by and some of these guides are real "characters" and can be very entertaining. It is customary to tip these "characters" at journey's end. You can take short trips between the Tower and either Charing Cross or Westminster or longer ones further upstream to visit Greenwich the home of the prime meridien and the famous Naval College. Try to pick a fine day for your trip as you will get so much more enjoyment if the sun is shining. It's miserable in the pouring rain.
A river trip at night is even more special, with all the buildings and bridges illuminated for your viewing pleasure.
Don't have time for a boat road, not to worry, a simple walk along the Embankment between Blackfriars Bridge and Westminster Bridge can be rewarding too.
Step 10: Take in a West End show
Step 11: The London Walks - I thoroughly recommend them
A new walk adding recently is called the Da Vinci Code walk, and this is one I plan to take on my next visit at the end of this year.
Step 12: Traveling light and make room for souvenirs.
Of course, camera is essential as there are wonderful photo opportunities.
Step 13: No needles or pins allowed!
The TSA provides a complete list of things you cannot take with you and you can check this out on their website quite easily.