Buy a ticket either by destination, or duration or top up a pre-paid oyster card. You can also use contactless
Work out your route and any line changes you need to make using the tube maps. Lines are clearly coloured & signposted
Disabled-accessible, step free stations (normally with lifts to platform level) are clearly identifiable via the maps
Insert your ticket and collect, or tap your oyster or contactless to the yellow panel to activate entry gates
When using escalators be sure to stand to the right to allow others to walk to the left
(Failure to do this may result in irate Londoners!)
When underground, follow the signs & use the line maps by each platform to ensure you're heading in the right direction
Overhead boards on each platform will keep you updated on when to expect your train (most run every 2-3ish mins)
On board: During busy periods move down into the carriages, do not obstruct the doors and watch your bags at all time
On arrival, be sure to tap out even if at a station without barriers to avoid contactless/ oyster being over-charged
Enjoy the buskers and free pianos around many central London stations!
You have reached your destination!