Two quick terms:
OOC: Out of character - acting beyond the fourth wall.
IC: In character - roleplaying your character.
Background
So, as we all know; our characters need a background story. What -is- important is that this background story will be affecting how our characters act, think and feel in certain instances. This is the core foundation of a character concept - for them to have a personality shaped upon their experiences.
It's important to make a believable story, and some times the "simple" story might actually be the best. It might be tempting for some to speak to a Bosmer who has been raised by Khajiit (yeah yeah I know, Dunmer by Argonians - see Brand-Shei), but the vast majority of roleplayers prefer a down-to-earth approach such as; Bosmer hunter started to wander the borders of Valenwood, fell into fighting with the necromancy-assisted imperials. Now, this allows for two set ups: A possible negative encounter with the imperials (could be a -very- big motivation behind his personal war) as well as a poor view on necromancy - depending on the imperials.
TL:DR:
Keep it simple - don't try to overdo it when a simple story can be the most interesting for yourself and the people around you.
Feelings:
So now that we got a character, now we need to take a look at his desires / motivations / situation. This is alpha-omega in roleplay. Portraying and -actual- character. Far too many times, people do not wish their characters to lose, for the simple reason of it making their characters look bad - even if feelings and circumstances go against them.
Feelings, as stated in the background, need to be based on experience in past events. As we all know; magic is distrusted by certain people (for example the nords) - HOWEVER: Keep in mind that it was not in the same degree during the Second Era as it is around Skyrim's time (the Oblivion Crisis, Great Collsapse, Great War, etc.)
Depending on your character's motivations, think on how he would achieve these goals. Is he a nord barbarian with little expertise in advanced warfare and strategy? Would he then go about planning the rescue of his loved ones from a great castle? No he wouldn't; he would seek help - like the NPCS (we'll get back to this), for example for a strategist from House Redoran. -THIS- creates roleplay, both for the barbarian, as well as the Redoran strategist - it's about being open.
TL:DR: Let circumstances and feelings guide your character, even if it makes them look bad - characters can actually be "good" in an OOC way by appearing bad IC.
The "Hero" and the Character's (Social) Power
If there is a way we're -not- supposed to go, it's to assign ourselves to the role of the "hero" of the game. This isn't a singleplayer game like Morrowind or Skyrim; and it would look stupid if every man and his cat went around saying he stopped Mannimarco and Molag Bal. Raids will surely be up for that, but here's the point - it's not classy, and raids should be considered purely OOC.
Here it's important to take on the roles of "NPCs" for ourselves. Does this mean we stand around all day, giving out quests? No - we simply roleplay as, for example, a city guard of Whiterun would. Here arises a problem, however - the scope of power: If there already is a -REAL- NPC who takes care of a specific task in game; for example the mayor of Camlorn - DO. NOT. assign this position to yourself. It is taken, we do not need players to fill this out - same with roleplaying famous characters from the lore. Sure, they may be around this period, and they may not be present in-game, but that doesn't mean we can actually ROLEPLAY them in their potential - as everyone view them.
As for the scope of power, remember that it is classy to keep your characters' powers "down" - depending on his role, experience and such. If you go into a confrontation with another player, his roleplay session can be -very- short if your character is a super saiyan (by the way, I hate anime and manga, you've been warned)
TL:DR:
Don't play the "real" hero of the story - take on reasonable "NPC" roles and don't force social power onto your character when it clearly isn't yours to take - be considerate of others, and do not roleplay famous people from lore.
Quick runup on Magic:
Keep in mind, however, that magic is -powerful-. One of the reasons people "hate" it is because magic is -unfair- and -powerful-. If we look at any high fantasy universe, we can easily conclude that, yeah, a group of soldiers < an experienced wizard. It's important to realise that magic might make your character scared, and is thus also a mental block. One of the few things I find interesting about, for instance, the Thalmor and House Telvanni, is also the -mental- pressure on their subjects. How would it feel if you had some cruel overlord above you, ready to smite you with a snap of his fingers if you didn't do what he says? Yeah, that'd be horrible.
TL:DR:
Magic is powerful; make it have consequences; and control yourself for the sake of others.
Actions have consequences:
If you think your character can walk into a bar, start a fight, kill a man and then stroll out like it was nothing - please don't play the Elder Scrolls Online, for the love of mankind.
A typical, yet stupid roleplaying flaw if for people to evade consequences from their actions - even those who roleplay people with political power. No matter what you do, there will ALWAYS be consequences for your actions - both positive and negative - no matter in what size and scope they appear.
This could also affect your character IC. If you killed a man's father - if drunk or something - your character might be able to evade jail - but he will OF COURSE have to leave down, as to not pay for his crimes. Even then, he will live with the knowledge that there's a chance his victim's son might hire people to track him down.
TL:DR:
Don't ignore the conequences that might arise from your character's actions - it can actually be fun to roleplay out.
Roleplay within the lore - don't gather "influence"
Yes, we get it - everyone loves Game of Thrones and everyone loves ninjas. Yeah well, here's the deal - I hate Game of Thrones, and I hate ninjas, and I don't want to see it in my roleplay. It's FINE that it exists, all power to the respective artworks - but it is NOT. PART. OF. ELDER. SCROLLS. LORE. The Elder Scrolls is NOT a grimdark setting - the closest thing you come close to grimdark is Skyrim, and that's nowhere near Game of Thrones.
As for ninjas... Whoever says that they want to see darkly-clad Assassin's Creed kind of fools roll and jump around on rooftops with katanas. Get out of my thread...
TL:DR:
Stick to the Elder Scrolls universe - don't gather influence from other works that can break the immersion.
More will come...