You can just step out of your door, map in hand, and walk, of course. London is one of the easiest cities to walk around - and I really noticed the lack of traffic, the amount of public transport, the ease of it all.
And there are some good options for "bulk buying" by getting passes and keeping your costs down.
The London Pass can be bought for one, two, three or six days and covers entry to 55 attractions including the Tower of London, Westminster Abbey, the London Bridge Experience, Shakespeare's Globe Theatre, a Thames River cruise, Churchill War Rooms, Windsor Castle, Wimbledon Tour Experience, Twickenham World Rugby Museum and Chelsea Football Club Stadium Tour. There's a 120-page guidebook which is good for planning, as is the website.
It also gives queue-jumping privileges at some places and can also be bought with a transport option - for unlimited travel on all public transport in London.
I used one and my advice is not to buy it for "several days". There's a lot to do that is free in London and, for example, you probably aren't going to use it flat out for six days. Plan a day, work out the usual entry fees, make sure the London Pass works for you and buy it for that day.
It is £44 ($70) for a one-day adult pass, £29 ($46) for a child, £52 ($82) and £32 ($50) with travel. At the other end of the scale, a six-day pass is £95 ($150) and £68 ($107), £145 ($229) and £93 ($147) with travel.
I was super busy and didn't get enough value out of mine. It is valid for 12 months from the date of purchase.
A great way to see the city. Look out for The Original London Sightseeing Tours and Big Bus Tours.
It's an easy way to travel by London Underground (Tube), bus, tram, Docklands Light Railway and on London Overground and National Rail services in London. You touch it on a reader at the start and end of every journey. For shorter stays, Visitor Oyster Card can be loaded with pay-as-you-go credit. It means cheaper travel, too - for example a peak single ticket for which you would pay £4 ($6.30) cash takes just £1.90 ($3) off your Oyster Card. Details at oyster.tfl.gov.uk. Buy from visitorshop.tfl.gov.uk or 3900 Oyster ticket shops around London.
Locals call them "Boris' Bikes" after London Mayor Boris Johnson, whose plan it was to have hire-bike stands all over Greater London.
Here's how the Barclays Cycle Hire works: put in your credit card, take a cycle, 24 hours a day, all year round, ride it where you like, then return it. You have to buy access and additionally pay for the time the bike is used.
As a guide, 24 hours access is £1 ($1.60), up to 30 minutes riding is free, up to an hour costs £1, and three hours is £15 ($23.80).
Nearly 143,000 people have used the scheme since it was launched last year. Go to tfl.gov.uk and click on Barclays Cycle Hire.
Trawl through visitbritain.com.