London can have it's share of inclimate weather and you won't want to be uncomfortable, so check the forecast and wear or bring along appropriate clothing. While Tube stations are underground and many bus shelters are undercover, when travelling by transit you will also be doing some walking as well as waiting for connections.
Always double check where you sat just before exiting any transit vehicle to make sure you've left nothing behind. People often loose wallets, purses, cellphones, umbrellas, jewellery, or bus passes on the seats of buses and trains. Loosing something like this can really spoil your day, so double check to make sure that you have all your belongings with you before getting off. If you do loose something try to remember the bus, train, or underground route, direction of travel and time of day when it was lost and check Transport for London - Lost Property to locate the phone number and or location from which to claim lost property, as this will depend on what mode of transportation you lost it on. The Transport for London Lost Property Office is located at:
200 Baker Street London NW1 5RZ Telephone: 0845 330 9882 (08:30-16:00, Monday-Friday except Bank Holidays)
If your trip is originating on a bus in Central London and you haven't already purchased an Oystercard, Travelcard, or bus ticket you must purchase your ticket from the vending machine at the bus stop with the exact coin fare prior to boarding the bus.
Be sure you are standing at the correct bus stop. Not all buses stop at all stops as they may be express. Most stops served by more than one route have the route numbers and names listed on the bus stop sign. Do not remain sitting on the bus shelter bench as your bus approaches - it must be clear to the driver that you want the bus or he/she may pass by. Indicate to the driver that you would like his or her bus by making eye contact and taking a step toward the bus stop sign. During rush hour buses sometimes fill up, but service is very frequent and another bus will be along within a few minutes.
To pay for you trip with the Oyster Card simply touch the card flat onto the yellow card reader, which if valid will emit a beep tone and display a green light indicating you can board the bus or pass through the turnstile, both when you enter and exit the system. If the light stays red you should check with an attendant.
Make sure you catch your bus going in the right direction. Don't just go by the route number. People often catch buses going in the wrong direction when travelling in unfamiliar surroundings. To avoid going out of your way ask the driver as soon as you get on to confirm the bus goes to your destination or transfer point.
Some bus routes are express, having limited stops through all or a portion of their route. This is good for getting you somewhere quickly, but not so good if the bus doesn't stop where you are going. It's always a good idea to confirm with the driver or conductor that the bus stops at or near your intended destination.
Most buses, and trains have an automated system which announces all approaching stops over the PA system.
All Underground and Overground Trains have route diagrams over the doors where you can monitor your progress towards your destination as you travel. There are plenty of helpful uniformed staff at the Underground and Train stations including at the turnstiles, so don't hesitate to approach them for assistance.
When travelling later at night don't miss the last Underground Train. Generally Tube service ends at 12:30am and on Sundays at 11:30pm. Remember these times can vary by station and line so be sure to check the Transport for London web site's First and Last Tube Times to be certain. To be safe I would suggest you be at a station at least 60 minutes prior to these times depending on the length of your trip. If you miss the last train you should be prepared to take a night bus or taxi. Night buses operate on designated routes in London and offer limited service through the night, but you may have to wait for up to 30 minutes. It is safest to sit near the front and on the lower-level of double-decker buses when travelling late at night. To see which routes provide all night service see London Night Bus Maps.
If you are travelling on any of the National Rail services you can use and Oyster Card for pay as you go or Travelcard trips, but only within the London National Rail Pay As You Go area. This zone is outlined by the red 'dot-dash' line around the perimeter of the map of National Rail lines leading out of London which you can download from the National Rail page. You must purchase a separate ticket for travel beyond this zone and also within this zone for the Heathrow Express or Heathrow Connect Service
You can also use the Transport for London Journey Planner to help plan your trip.
Quick Tube Tips: Always stay to the right on escalators and stairs to allow hurried commuters to pass. Allow passengers to disembark from the train before trying to board. Remove any backpacks from your back prior to boarding. Stand well behind the yellow line on train platforms while waiting. Avoid rush hour travel for a more relaxed trip. Watch out for pick pockets in all crowded public locations.
The bottom line is to study the maps and plan ahead. A little time spent doing this ahead of your days outing will help you save a lot of time and frustration. If in doubt ask questions at the start of your trip, not later when you may have to backtrack.