Transport for London allows you to map out your entire route at anytime of the day. Choose to see all modes of transportation or select specific types for your journey. The site also provides the most up-to-date status of the tube lines in London, a very useful source of information especially on the weekends!
Tubes are the fastest mode of transportation in London, but also the most expensive. Unlike the metro or the subway that allows you to enter with one ticket and continuously change lines until reaching your final destination, the tube system tracks your journey. This means you do not pay for your journey until the end of your trip. Once you use your oyster to exit the station, you will be charged based on the distance and time of your journey.
If traveling many places by tube in one day, I suggest purchasing a day pass for around £7. I typically used my Oyster card (a transport card that you reload regularly at convenience stores or tube stations), but when friends came into town and I knew I’d be traveling a lot, I purchased the day pass instead.