During multiplayer the trick gets displayed while your game loads, then you go in to the game and wait for the other players. One could make it so that you can still display that trick, so one can finish reading it while the others connect. But you should also be able to check your base, where trees are etc.
There's a important typo in 0ad/binaries/data/mods/public/gui/reference/tips/texts/select_wounded_units.txt The hotkey is "O" (the letter) not "0" (zero).
These are my tricks I'd like to share. Could maybe be phrased better and/or shorter.
I made 3 tricks in a series called "Fight, flight or let them ride?". It seems a bit obvious, but it's important and a lot mistakes are made here.
I split it up to 3 so one can read it hopefully in one loading screen.
(Fight)
Fight, flight or let them ride?
If there's a fight going on nearby between two equally strong factions and some units are gathering resources they should definitely join the fight.
If all units are occupied fighting any additional unit:
-receive no damage at all
-can deal additional damage
It is very crucial to have the higher numbers in a fight.
(Flight)
Fight, flight or let them ride?
Estimating army strength is crucial. If you notice a enemy army gains a slight upper-hand running is often the best choice as your disadvantage will only grow bigger.
Only keep fighting if you are willing to sacrifice more units than your enemy for a very good reason. Don't expect that a bad fight turns better on it's own.
(Let them ride)
Fight, flight or let them ride?
Assume a small group of attackers run around your base.
Do not overreact and send too many men to chase them!
Running units are not productive. If your enemy has a few units running and a few producing while you have all units running your enemy will flourish.
In a fight you want to keep the upper hand though. A seasoned commander reacts to these situations in appropriate way.
Anticipate supply and demand.
When all men go to battle consider moving some woman from the fields to replace male wood gatherers right away.
Garrison forts!
A battle is going on. Garrisoned units in forts, civic centers and towers can safely deal damage from within the building.
Garrisoned units usually deal less damage from within the building. Select wounded units with "O" and garrison them preferably. This way they avoid soon death and can serve you longer.
You can repeat this while the fight is going on. Once the fight is over they may be able to heal up and be stronger than new units through their gained ranks.
Teleportation:
Units can enter and leave buildings from every angle instantly. You can use this behavior to transport units over the distance of the building.
Command the units to enter the building, set the destination with the way-point flag of the building, with the building selected hold the U-key.
This can be helpful e.g. for ranged units to gain some distance from melee units or vice versa for your melee units to close the distance to ranged units.