Even people with cars use public transport in London. The system is practical and covers most of London and the greater London area. It is composed of trains (overground), tube (underground), DLR (Llght railway), river boat, cycling lanes and tram.
There are always people on the bus, train or tube so it is safe to travel at most times, however as in all cities, thieves haunt busy areas and it is always wise to be careful. Do not leave your luggage unattended and make sure to keep wallets and purses out of sight. Night buses run after 12:30am and as they might be less safe because of the time of day, you will feel more comfortable if you sit near the driver.
Nuisances are not tolerated and drivers have the right to remove (and they will) any passenger causing trouble. Buses, tubes and trains are cleaned regularly but during the busy commutes, garbage and waste may appear. The good news is that many people leave their newspapers behind for you to read. Smoking is not allowed in stations nor on public transport.
Lost property: Always inform the police if you lose anything if only to validate insurance claims. Contact the nearest police station: http://www.met.police.uk/local/.
You can plan your journey ahead by consulting Transport for London website: http://www.tfl.gov.uk.
You will need a map: http://www.tfl.gov.uk/gettingaround/1106.aspx.