First the basics:
Your character details are very important, not only for you but others as well! We start with the race.
Race is one of the first thing another fellow roleplayer will notice, so you have to define your characters place in the world. And then you may think "I picked a boring human!! Aren't they all the same?" Answer: NOPE!
Humans will be different depending on where they are from, people from Iluskan are humans like the people from Thay but they are VERY VERY different, both in culture and physically. Same with kara tur humans, etc. So always have in mind where your character comes from, it will help you break the ice many times or it will sometimes even decide if your characters are hostile to each other ( like elves and drow or orc, dwarves and orcs, etc.)
This website (and many others on the internet) touch on how faerun humans are different from each other in the world.
https://www.realmshelps.net/charbuild/races.shtml
Now that race is out of the way, let's talk about your character class and planned path. Most people plan their class up to level 30 even before making the character, others do not. This is fine.
The most important part of your character class is the WHY, WHEN and HOW.
Why did Mike decided to take paladin oaths? Did he have a vision? Was he inspired by other knights? Whatever class you picked for your character, make sure that your character can tell others why they picked the path they did. Passion for fighting, hatred of the orcs, researching all the threads of the magical Weave? Anything is valid! Remember this is your chatacter and YOU decide.
"But I don't know anything about this lore yyj!!!"
Well just look for resources on the internet. Here is a great one.
https://www.realmshelps.net/charbuild/c ... ndex.shtml
When did they decide to learn their tools of trade? An orphan child who had to learn to hide and move silently to steal and pick pocket for a living? A prisoner conscripted into a foreign army and taught how to battle? Who knows! But this is a very good opportunity to roleplay with other characters, giving depth and realism to your interactions.
How did Laura become a wizard? Did she study on a magic academy? Was she taught by a hedge wizard or maybe she studied on her own in a giant library? Another great opportunity to write a character, you get extra points if you use an already existing NPC on the world as your mentor/teacher (because this also gives the DM an easy oportunity for events and roleplay).
Again remember to look at the realms helps site (or the books if you own them!) To make sure that the story makes sense.
I hope that with this small guide (I use the term loosely here) you can flesh out your character better and have more things to roleplay woth others.
Below I will give you a few tips that I try to follow always:
Don't look at the player name, just treat every character like their own thing, if you do look, do your best to just not take into account who the player is.
Try to keep OOC chatter to a minimum, if you can say something OOC like you have to go, you can also do it IC. Of course OOC comms are necessary sometimes but not 100% of the time.
Always be ready to clarify why your character does something if people asks. Sometimes this can break immersion, but cooperative roleplaying is done with others and we have to account for our fellow players to keep the wheel rolling.
Be ready to forgive your fellow players mistakes. Yes we all make mistakes and we aren't perfect and neither are pur characters. We all make mistakes so let's all try to all forgive.
Offer your help to newer players!
And finally, always look at how to make formal DM requests. DMs are your friends and are here volunteering to have fun and play with us!
Anyone feel free to comment on this guide, even if you disagree! (It bumps the post anyway

Thanks for reading <3 <3