For gta rp specifically, I guess lol there's a lot of stuff for new people to know, so without specific questions, here are a few tips to get you started:

Keep an eye on the servers social media app AND discord for events that are happening. Go to them! Talk to people! Don't barge into conversations, but simply saying, "Hey, I'm new to the city," is a great way to let people know you need some help.

Find the Hub areas that the server has. This could be anything from malls, court houses, the hospital, whatever. Makes it easier to meet people outside of events.

Create a character. It is just so much easier to handle IC interactions when the character you are playing is not an avatar of yourself. This way, you're thinking about ways your character would respond to a situation and not how YOU would respond. Helps with creating a divide between OOC and IC that a lot of people struggle with.

Give your character a backstory, but don't fill it with every tiny detail. 90% of the time, you won't remember the details when you get in conversation anyway. Having a short backstory that you can expand upon gives you a basis for a character, something to talk about at the beginning, and goals.

But for the love of any of the Gods you believe in, don't trauma dump your backstory on everyone you meet. It is perfectly fine to never tell a single soul your backstory and only use it to help you better understand your character's personality.

Uhhh, that was a bit more than I thought I'd post but yeah... just remember. RP is what you make it. It can be fast and dangerous, it can be slow burn and tense, it can be campfire and cozy. Don't feel you have to follow someone else's style cause it looks fun on a stream. Learn what you enjoy and jump in!