I think this is an OK place to start (you can also look up other RP guides for newcomers online, generally the same basic principles apply no matter the game and there’s a few groundrules and linguo that you should be aware at first).
You’ve done a good chunk of the work already, namely that you have ideas. Don’t be shy to express them here or some discord you’re part of (doesn’t hurt to join one either since those are the main tools people use to find roleplay and/or rp connections these days. there are either more ‘general’ ones for the server as a whole or each faction or more niche/community ones such as discords for x race) to get feedback. You won’t get everything right the first time and that’s ok, it’s important to learn from the mistakes that you make. We’ve all been where you are.
Take the ideas you have and apply them to the race and class you chose for yourself (though do note that even if you do play a priest, your character doesn’t actually have to be one, they can just be a commoner and never use any priest abilities or in time they can grow to become one). I would say it’s going to be a bit more tricky to play one of the ‘ancient’ races such as night elves but it’s not outright impossible. Spend some time to read about their culture, history, what happened to them in game recently if you don’t remember from your questing etc.
Argent Archives (look it up online, I can’t post links to the website) is also a good place to look at characters, stories and incoming events so you can both get an idea of how people work on their roleplay and also find initiatives where you could take your character.
best of luck and all that