Immersive playing vs "it's just pixels" There are two general ways of acting in virtual worlds like Second Life or those running on OpenSim. One is the "it's just pixels" way of seeing OpenSim as a chat platform, barely caring for the virtual world around them and putting convenience above everything else.
The other one is immersive playing. It means seeing these virtual worlds as such, as wide-open role-playing sandboxes, and their avatars as characters in these worlds, and putting realism and immersion above everything else. It is not, however, as extreme as hard roleplay that involves character sheets with character stats (strength, stamina, dexterity etc.) on them, going on pre-scripted quests or throwing dice much like in Dungeons & Dragons.
I'd like to explain these two concepts here.
"It's just pixels":
Your avatar is nothing but a profile picture that more or less represents your real-life self in a 3-D chat app. Same goes for all other avatars: You assume they only represent their real-life users.
Your avatar never interacts with other avatars. It's always you interacting with the real-life people behind other avatars. Always.
Never act in-character because your avatar isn't a character. It's just a profile picture that represents real-life you. So there is no in-character or out-of-character.
Put real-life info about yourself on the "2nd life" page of your profile. Don't use a picture of your avatar as your profile pic because your avatar IS your profile pic. Disregard the "1st life" page, it's useless, and navigating to it is more inconvenient than simply throwing everything on the "2nd life" page.
Keep your viewer always set to midday. You couldn't see anything otherwise. (Side-effect: You'll never notice that you've got lots of glow-in-the-dark things on your own sims that shouldn't glow in the dark like plants or entire buildings. You'll never see your own sims in the dark.)
Wear the brightest facelight you can find because the sun throws ugly shadows on your face when it's constantly standing vertically above your head. Or switch your body and all your clothes and attachments to full-bright.
Never walk. Never use vehicles either, they're too slow. Prefer teleports directly to your destination because that's maximum convenience. If you can't teleport, but you can fly, then fly. Fuck realism. Or land on a sim, keep standing at the landing point (even if you're standing on someone's head with someone else on yours) and cam around. Hate teleporters that only work by walking into them with a passion. Demand all teleporters be clickable.
If you go to a party, prefer teleporting or being teleported next to the dance floor and automatically oriented so that you face the dance floor. Or right onto the dance floor.
Leave parties by teleporting away or logging out while still dancing. It's the most convenient way because it requires the fewest mouse-clicks and the fewest steps to take.
Take landmarks of sims either right where the action is or, if there's no action, right at the landing-point.
The only in-world objects that matter are sales boxes/vendors, whatever you can copy that's interesting for you, scripted dance floors, dance pads, dance machines, teleporters and maybe sex furniture. Disregard everything else.
Beaches are only there for beach parties, as a justification to be naked or for public sex. Own beachwear only to flaunt your body while staying within the G-rating.
Wear what you always wear, regardless of where you go. If your avatar is male, wear a black leather jacket, long jeans and black leather shoes (or even black biker leather from neck to toe) on a tropical beach. If your avatar is female, wear a thin, sleeveless micro-minidress, ultra-high-heeled platform sandals and no hosiery whatsoever on snow-covered Christmas-themed sims. Pixels never get hot or cold. And it's your right to look as badass or sexy as you want wherever and whenever you want. If someone kicks you out of a formal event with a mandatory dress code for breaking the latter or even bans you for doing that repeatedly, rate the sim where it happened zero stars on OSW and insult the sim owner.
Finally, insult immersive players for being idiots who do dumb and weird shit and try to explain to them how to use OpenSim the "correct" way.
Immersive playing:
Your avatar is a character in a virtual world, one that interacts with that virtual world. Other avatars are characters, too.
Your avatar interacts with other avatars like video game characters would interact with other video game characters, or like role-play characters would interact with other role-play characters.
Always act in-character because your avatar is one, even if it represents you. If you have to act out-of-character, put it in ((double brackets)). Bonus points for making your differently-named alts characters of their own with no connection to your real self whatsoever and their own fictional background. More bonus points for even giving your main avatar some in-world lore, thereby confusing the "just pixels" faction that takes it for your own real-life background.
Use the "2nd life" page of your profile only for in-world/in-character info. If you absolutely have to give real-life info away, use the "1st life" page for that.
Keep your viewer on "shared environment" unless you need different lighting for photography or for immersive purposes. Or even build your own more realistic EEP day cycles. It's just a pity that only you can see them.
Don't wear facelights or bodylights. Are there facelights or bodylights in real life? No. See?
Walk or use moving/steerable vehicles whenever possible. Only teleport as a last result, and even then, try not to be seen. Hate buildings that substitute stairs with teleport pads (maybe unless the teleporters are disguised as a lift). Don't fly unless absolutely necessary due to how badly the sim is designed where you are (e.g. no other way to get out of the water). Don't cam. You can't teleport or fly or cam in real life either, right?
If you go to a party, prefer teleporting or being teleported to somewhere that can't be seen from the party venue and then walking to the party. Ignore any and all teleport offers because they'll land you right in the middle of the crowd which is exactly what you try to avoid.
Leave parties by walking outside to where nobody can see you teleport away. If you have to teleport, that is. If you don't, then walk or use a vehicle. If you can't go outside because the venue doesn't have doors, try hiding somewhere.
Take landmarks of sims in places where you'd realistically arrive, e.g. harbour quays, marina piers, bus stops, railway stations, airports or the like. Go back to there to teleport back out. If nothing like that is available, take it where it's unlikely that you're being seen teleporting in.
Everything in-world matters, everything in-world can be interesting. Complain about furniture that looks like you could sit on it, but that you can't sit on. Play with your surroundings. For example, if you come by a supermarket, pretend you've yet to get some groceries.
When you're on a beach, take a sunbath. Or go swimming. If you can't go swimming because the beach isn't designed for that, the beach sucks; find a better one.
Dress appropriately for the location and the occasion. Wear summer clothes in summer. Wear beachwear on beaches (or nothing at all on nudist beaches that ban clothes). Pack yourself up well in winter. (Yes, even female avatars can do that. Yes, that'll take some searching around and/or asking others. If it's possible and has been done with a Ruth2 v4, why should it be impossible for Athenas?) Wear something in-between in spring or autumn. Generally, wear something comfy in your spare time instead of always dressing up like you're on your way to a club party. Wear a tuxedo or a gown to formal events; take that opportunity to dress up to the nines. Wear sturdy shoes when wandering.
Finally, complain about the "just pixels" side for breaking any resemblance to immersion all the time.
It's fair to mention, though, that there aren't only these two extremes, and you can always be somewhere in-between.