Another good thing to think of while roleplaying is how to play well with others. You can have a powerful character, or even one who's an ass. But if you don't have experience with it, it wont go well. Try not to go in swinging by insulting characters you don't know, or make them feel inferior, because the person rping them is gonna be put off and not want to interact with you.

I'd start off with an approachable, cookie cutter character, and then develop them from there. Just to get some practice and figure out what you want from rp.

Though honestly for character story, do whatever you like. Elder scrolls lore is so weird, and also inconsistent in many areas, that you could do literally anything and find some creative way to justify it. I could probably give a character a tank and say something like 'yeah its an old lost dwemer prototype weapon' and no one could say I'm wrong.

Most guilds though want to keep characters and lore in a specific fantasy aesthetic though, so I'd check with whoever you decide to rp with. As a general rule though, keep within the medieval fantasy vibe and playable races.

There's usually some kind of public rp going on in the inn in Evermore I think. Otherwise, browse the rp section of the guild finder. You'll probably find a nice group to rp with, I found mine first try.

I'd suggest joining a RP Guild.
I find only a few players actually roleplay in this game, it's mostly mute combat.

many years ago i joined a great RP guild even though i could not RP at the time and it was great, after doing other things and returning to ESO i found this guild and nearly all other RP guilds had become a thing of the past. I think there maybe a couple of RP guilds listed in the guild finder now that maybe worth taking a look at. you could just apply and check out the scenery then decide if it's what your looking for.

I'd be even more basic - make sure to be approachable (while roleplaying and outside of roleplaying). I'd also advice you to begin with listening in, see how other people roleplay in the game - not that always means you will see "good" roleplay but it helps with a genereal setting of the world. Personally, I also like to do some roleplay while being alone in a tavern or even so a more secluded area, getting the emotes right and just feel comfortable to go "in-character".

As others mentioned I'd also recommend Discord for RP communities.