Please explain to me like I'm dumb - how do I use the tube?

Download a map of the entire system.

Study the key. Note different colours of the lines, and all the symbols and what they indicate.

For instance, you can connect to other lines at some stations, indicated by white circles on the map. This makes planning your route easy.

There are maps of the route posted inside each carriage. Check where you are and compare to where you think you should be after your train arrives at the first stop after the one you got on at.

If you realise you're going in the wrong direction, hop off (or, don't panic, and hop off at the next station) and switch to the opposite direction platform. It will be signposted.

freetoursbyfoot.com/how-to-use-the-london-underground/

Handy guide ^ to the Tube.

When you are faced with those boards showing all the stations on the line, mentioned upthread, it's easy to think you've got to pick out your station really quickly so that you can get on the train, specially if you can hear one coming.

You don't. The trains are so frequent during the day that you can take your time, pick out the station you want, let the approaching train go and be sure you are on the right platform waiting for the right train and the next will be along in a few minutes. The slightly longer wait will be a lot quicker than going the wrong way and having to return.

Wow! I did not know that! Off to London next week and have just set express pay on my phone.

When I first went to London I did not know that that once you were on the tube system you could change lines underground. At every interchange I took the escalator to the surface then bought a new ticket to the next interchange. 🤣Just a thought.
I am sure everyone knows this but just in case.

Nursery school generally has fewer bell-ends.

You can use Apple Pay or G Pay

This is really good advice.
Don’t worry. The staff are really helpful. And everything is really well signposted.
Golden rule - on escalators stand on the right, walk on the left!!
Have fun!! London is my favourite city in the world!!!

We're going for Saturday and Sunday

An Oyster card costs £7 so if you’re just going for the day it’s not worth getting the discount. I travel into London regularly so it’s worth me paying the one off £7 to get the third off.

Download the TfL app.
Type in where you're starting from and finishing. It will tell you the quickest way, step free way, bus only way.
On the tube tap in and out, on the bus tap in only.
All lines are colour coded and really easy to follow
Use the same card or apple pay for the whole day so if you are using it a lot your total fare gets capped. Don't use Apple Pay for one journey then your debit card for another
Also some stops are so close it's quicker to walk. If you are going to the usual tourist spots London is really easy to walk around

CityMapper (App) is really useful for telling you which Tube to get on and in which direction.

I think you used to have to use Oyster or a ticket before contactless got trendy

I am going to London tomorrow till Sunday
I haven't been for years so not familiar with oyster card.
But I saw your post. I have a disabled Railcard.
What is best/cheapest for me to do?
Should I get an oyster card? And how do I do that?

Main rule. Stand on the right on
The escalator.. Any suitcases keep in
Front of you on the right. Walk on the left if you want to move quickly. You will be shouted at by a local (sorry) if you breach this and stand on/block the left.
Do not stand to talk/sort about bags at the top or bottom of the escalator. Again you will be shouted at.
Tap in and tap out with same card (contactless or Apple Pay).
Use citymapper.
Enjoy, and do check as sometimes walking is just as quick.

Mostly the boards are next to each other so you don't need to know which way, just look for the station youre heading for... (looking at both boards) ...

Thanks for citymapper suggestions, that looks a lot better.

Download Citymapper - it will tell you the best route to take and what form of transportation

It’s the north or south bound thing that’s VERY stressful. “Just look on the boards” can be baffling if you have no idea which board you should be looking at to find your stop.

The TFL journey planner on my phone is helpful but it makes absolutely no mention of which direction you need to be going, north south etc. Just says get the Picadilly line to Holborn or something.

Funnily enough when I’ve been to Paris, they have a similar online journey planner and they say towards XX stop. I’ve been far less stressed using the Metro tbf.

Download the citymapper app. It tells you which timeline, when, what direction, where to change in real time.

I have just come back from a few days in Greenwich and I’m missing London already. I think everyone has covered the most important things but I would encourage you to venture outside of zone one. London has some of the best public transport in the world, so don’t be afraid to explore and get lost a little (although with Google maps that’s incredibly hard to do) you’re never ever far from a bus stop.

I miss the one day travelcard for zones 1-2 and zones 1-4.

The station (if it has more than one line) will have colour coded directions to each line.

Follow the directions to eg Victoria line. Then when you're at the right level for that line it will say eg Victoria line northbound on one platform and southbound on the other.

If you don't know which direction (I'm very familiar with using the tube but I can't always think on the spot, am I going north or south, east or west) just look for the station you intend to go to on the boards and choose that platform.

Even if you get on the tube and then realise it's not the right direction, it's generally quite easy to get out at the next stop and walk over to the opposite platform to go the other way.

The one thing that bugs me about getting on the tube is people on MN etc say ‘ just get the Victoria line to Oxford Circus and get off at Covent Garden or whatever.’

But for none Londoners like me and OP, the main worry is… what direction? You lot know - but us lot have to panic when we’re at the station and changing to the next line and stressing about towards which direction? It’s really not that clear sometimes

A few thoughts: Get hold of a tube map before you start your journey. Work out where you want to go and what line you need. Work out if you need to change lines and where.
If you have a wheelchair or a buggy some stations have lifts. People are usually helpful if you need to get on and off with a buggy etc. Try not to do this in the rush hour if you are uncertain.
If paying is worrying, you can get an Oyster card from a London station, top it up and pay with that. It stops the worry about tapping in and out. They work on buses too. London buses are cashless but will, like the tube, take a credit card.

Carry a map with you.
Good luck.

Sorry haven't rtft but worth noting (if there are various routes for the same journey)

Central line, Victoria line, northern line are some of the deepest (and hottest) tube lines.
The met line is largely above ground if you don't like being underground.
The Elizabeth Line is new, more modern and has air con.
There are usually staff at barriers who will be able to advise if you have a problem or question.

Hope you have a lovely time visiting.

Nothing to add to the sensible responses.