Here, we post important lessons in gaming that should seriously apply to real life aswell, because they're cool and all, and would make life soooo much easier. Stuff like...
- falling from 1000 meters kills you, unless you end up in the water
- carrying a big gun in your hands slows you down, unless you put it in your bag and carry a pistol instead
...and so on. May the carnage begin :O

You can completely heal yourself by eating candy and drinking from fountains.
Your small invisible backpack can hold several units of Full-Plate mail.
Jumping while jumping makes you jump higher. But a ledge higher than your waste cannot be jumped onto.
You can cross the country in 30 minutes. Or a few seconds if you press down somewhere on a map.
If you remain still for a while, you will experience an out-of-body experience where you can zoom in on your own 'features'.
Mr. Tilde is your friend.

- Game worlds are invariably more interesting than this dump we live on.

Secret doors don't cast shadows (Quake).
When your fingers aren't quick enough, use the spoon (SEGA Olympics, Prince of Persia)
I'll leave the rest to others :)

Praying to "God" (AKA: Console) allows for some of his powers.
Sometimes people are just too stupid to get to you.
Sometimes even the best healers can't heal stupidity.
Real-world networking can be almost completely automated.
Always expect something bad to happen when things are finally going right.
The weight of equipment doesn't matter so long as you have enough space.
Hammerspace is the most useful kind of space.
[url=http://video.msn.com/?mkt=en-us&playlist=videoByUuids:uuids:d5063c1b-ec0e-42e5-98bb-0ee5ba814153&showPlaylist=true&from=customplayer_en-us_xbox_watchtheguild&fg=cp_en-us_Xbox_Channel_TheGuild]Life is easier to measure with experience points.[/url]
Excel is fun when dealing with spacecraft.

cows are perfectly able to talk, use weaponry and even cast spells

Knick everything not nailed down; if it is nailed down then a) solve the prying-the-nails-off-the-kit-you-are-after mini-game b) find a crowbar c) if all else fails read some books/eat some Mentats THEN solve the mini-game.
Power armor and gatling laser = never having to say you're sorry.
Charisma CAN be useful at times.
Stealth kills are far more efficient and waste less ammo.
Life needs a reset/reload function.
IDDQD.
up up down down left right left right b a select start.
A crowbar never runs out of ammo.
You can punch a Cyberdemon to death.
Kill the medic.
Magic doesn't exist in real life.
Magic and technology do NOT go well together...
Water, in some games, can be radioactive...
But the most memorable lesson I have learned from gaming?? It goes a little like this:
What can change the nature of a man?

Perpetual motion is entirely possible with turtle shells.

The best way to find a job after moving somewhere is speaking with every single person you see around you.
However, the best way to get some money is to visit every single cave in the area.

It is perfectly acceptable and totally not dangerous to shoot/stab your friends with any myriad of weaponry ("no friendly fire" settings).
If a giant hand comes out of the sky and tells you to go somewhere, it's probably sending you to your death (strategy games).