1. Figure Out What Kind of Roleplayer You Are.
There really is no wrong answer here. Whether you're more of a talker or a doer - your personality needs to compliment the character you're playing. If you've never played before - you may have no clue as to what kind of roleplayer you are and that's okay!
To make it easy you can boil it down to several archetypical ways to roleplay.
The Actor: This is the person who wants to act as if they are the character themselves. (my personal favorite). They may adopt a new accent, mannerisms and a different personality.
The Thinker: This is the person who takes notes, lots and lots of notes. They know every NPCs name, backstory and where they come from - even if it has nothing to do with the main story arc.
The Achiever: This is the person who wants three things - Experience, Levels and Loot. Their passion for the game is getting whatever they can get done to make their character even more powerful.
Keep in mind, I firmly believe there is NO wrong way to play AS LONG as you're being an asset to the group, not wasting anyone's time and most importantly - having fun!