Hello and welcome to the community. As a lot of these kind gents have said, a lot of what Roleplay is is creativity. It is having the ability to adapt and creatively assert ideas and interjections into a situation to modify it.
There are multiple types of roleplay, and you'll find them all here in Altis. There is the Dramatic RP. This usually entails a lot of fiction and can create very long sessions of Roleplay. For example, you have an illegal weapon, you are a Rebel. Within dramatic RP though, you're not a rebel, you are a man on the edge who's only love has been taken and is being held hostage unless you settle a debt you built up with your outrageous gambling addiction because you have a poor taste in alcohol and poker and use these as tools to ground you back in reality because you can't believe your wife might actually love you, you feel you don't deserve her and through your own actions create a reality where she won't....but she will continue to...anyway, by doing this you now owe certain people a lot of money, beg, plead with the Police. Your wife's life depends on you paying this back, and how would they feel if the Police showed up?....
Within the reality of the game, this is all bullshit, but it's up to you, your skill and your dedication to your story and your RP to sell this story to the Police and other people. Make them interested, make them want to be a part of your story. Do it right, and you'll have cops working with you to find out where your wife is being held, who's holding her and how they might save you all from this terror.
That, is dramatic RP. Or you could go for the Realistic RP. This is where you accept what you actually are, that rifle you are holding, that's not a lawnmower, that's not a blender. It's a rifle. You are a badass motherfucker who's trained with Navy Seals and gambled with Dan Bilzerian. You've found out how corrupt this bullshit Government is and you are making a stand. You're caught robbing a petrol station, yeh that's right, none of this "Oh sorry I was buying a box of Cornflakes and my gun slipped out into my hand and I aimed it at the staff member for a very long time...but it was an accident...honest" bullshit. No. You are a criminal. You were there to rob, steal and scare so you could further your cause that the Police don't save everyone. People shouldn't work for pennies and live such a feeble existence in a sheepish bubble hoping a "nanny state" will take care of them.
Finally, there is barebones RP or...excuse RP as I call it. This is where you have no intention of creating a particular fiction, instead you will use Roleplay as an excuse simply because you do not want to arrested or killed.
An example of this - "Shoots a civilian". Police turn up, begin searching people close by, find an illegal firearm on you "This isn't a firearm Officer, it's a phone charger". Officers inspect this for a few minutes, and agree it is simply a phone charger, as a result of this, they let you go and leave the area. When they do, you then use it as a weapon again. This. This is bullshit because it shows your inability to RP and stick to a fiction you have created.
Another good one is when you are wanted, you are driving your car and are stopped by Police. Police will ask if you are the owner, you will reply "no. My cousin owns it". When asked where your cousin is, you will respond "I dunno...he's not on the Island". This is basically bullshit because you can't be bothered to create a fiction however don't want to be arrested either. So you simply come up with the most bare minimum you can that keeps you in the clear.
Anyway...good luck