After finding this in my inventory I figured I'd add it here as well.. a bit old text, but still very valuable advice. ;)
The A to Z in SL AKA Kiana's guide to newcomers...
AO (Animation Overrider) - A must have! Nothing else needed to say about this, just get one, any of them is better than the noob walk and stands.
Boobs - Now I struggled here for a few minutes whether to add building or boobs and boobs won.. after several years of battling with women's shirt and boobs issues, some genius decided to create a cleavage with a skin texture. Kiana bows. Finally I can wear 'normal' shirts without having to separate my boobies.
Creativity - This is what SL is about and what I love the most. You can create anything you imagine and more. This world is full of possibilites. Don't stick to the norms or care about what other ppl think of you, experiment with your mind and let your creativity shine.
Dance huds aka Chimeras - Get it loaded with hot dances and you'll never be alone on the dance floors again. The next step is to learn those dances in the real life without hurting yourself...
Expose hidden weapons, huds, traps and other 'secrets' by pressing Ctrl+alt+T
Friends - You can definitely create real friendships in a virtual world. Be a bit cautious though, before revealing your deepest and darkest secrets, many people want to keep SL separate from RL.
Groups - Not only you get a cool tag and nice group spam, but you can find like-minded people inside groups and they are also essential for building purposes.
Hate the lag? Make sure to clear your cache on a regular basis to get things run smoother. Stripping off all scripted objects helps too. Nowadays even hair and shoes come with scripts, but you can delete those - the scripts, not the shoes...
Instant messages can get capped if the user is offline, so send important messages preferably on a notecard and make sure to edit your preferences so that your IM's are forwarded to your email.
Join me in 'This place' - Be creative with teleporting friends and send silly messages like 'Set midnight and land straight into my lap'.
Keep your inventory organized - Make new folders under different categories and save a lot of time. Something that some of us should have done a few years ago already instead of struggling now..
Lucky chairs - Wait for your initial to pop up and win something cool (or waste hours to get boots that don't even fit..)
Music - All genres of music, everywhere! Amazing talented live artists and dj's at cool clubs. I always have SL streams on wherever I go, it simply adds to the athmosphere.
Never give up, it takes a while to learn how to do things and find the places and activities you enjoy doing here, but it's definitely worth it! SL is like 'Hotel California', you can checkout anytime you like, but you can never leave!
Original gestures will quickly get you popular in clubs - Find the rare stores or make your own and go crazy!
Poseballs - Hoooo! for poseballs! Test them alone or together but without them sl would be a boring place.
Quicktime - Make sure you have an updated version, it's essential in SL.
Ruth - Sometimes you end up in this nightmarish formation of a mixture of you and noob! Argh! If clicking appearances won't help try to relog and hope for the best...
Sitting - The golden rule in SL! With sitting you can a) avoid griefers that push you or annoy you with their weapons, simply build a basic 1 prim box and sit on it- works as a shield against most weapons!
b) use this same method to get inside any locked building, just sit on it and use the arrows under EDIT to glide
yourself through walls - remember that this won't protect you from possible security orbs...
c) areas where you can't build or place objects down, just use your camera to get inside a house, find the closest chair and sit on it.
d) you will also get out of some traps by clicking the top of the trap and sitting on it.
Traps and weapons - Loads to choose from, but get geared up with the best ones and have hours of fun annoying your friends (until they buy even better ones and when you're trashed for the 10th time the fun kinda disappears...)
Unique - Why in a world where you can be anything you want, many end up looking exact copies of each others. Create your own unique look to separate your avatar from the masses.
V + ctrol + alt - instant FLY everywhere among other superpowers
Wings - Spread, flutter, ruffle or do whatever you want but it seems everyone needs at least a one pair of them here at some point.
XX or XY - Nothing in Second Life is at it seems. Anyone saying that she is a 'voice verified female' usually isn't. Be careful, this is a world where genres mix and people have multiple alts. You never truly know who is behind an avatar, so make sure to keep an open mind.
You - You make sl to what it is! So, get out there, speak your mind, explore, influence and learn.
Zoom - You will be totally lost until you learn to use your zoom.. seriously - practise! (Our ChromaSphere game is a cool toy for learning to use camera controls).