"Better" may mean different things to different groups, so it depends somewhat on the play style of the GM and other players.
If you have a group that is heavy on the role-playing side, don't be afraid to step outside your comfort zone. It is sometimes a challenge for new players to speak "in character" because it feels a little embarrassing when you are new to the game or group, but getting comfortable with that aspect of role-playing can lead to some of the best in-game moments. Don't worry so much about trying to do an accent, or speak with some other affectation; just use your own voice but try to think about how your character would react in the given situation. Instead of speaking in 3rd person like "My character says...," just speak in the first person, "I am honored by your presence, Duke NPC". Check out role-playing podcasts that discuss 1st person vs 3rd person. Google "Fear the Boot" and peruse their role-playing show topics.
If you have a a group that really enjoys tactical combat, it's important to understand how your character's feats/spells/maneuvers can aid the other characters on the grid. You might want to do some Google search on class optimizations / builds. Read through the combat section carefully. Understand how flanking, feints, aid another and other in-combat maneuvers can give you or you allies bonuses. If you are a spell-caster, research the use of buff and de-buff spells beyond just damage dealing spells. As an example, "Grease" is one of the most powerful utility spells in the game.
In terms of helping the GM, listen to the descriptions given as the GM narrates a scene. Ask questions about the details of the objects and surroundings of the scene. Ask about your other senses (smells, sounds) as the GM may sometimes to forget these details and the interactive give and take of noting these small details can really help a GM's creative juices as well. Honestly, as a GM, I am brought up to another level when the players ask leading questions. Sometimes I don't have all the answers, but other times it suddenly occurs to me that I can add a clue that I might not have otherwise thought to include or gives me inspiration on how to to build more atmosphere.
Don't be afraid to ask questions of the more experience players, but remember that it is your character, so have him or her act as you wish. You don't always have to act in accordance to their advice or desire.
Lastly, thank the GM for their game. It takes a lot of prep work and it is often thankless. At the end of the night, note something in the session that you thought was really cool, or particularly fun about the session. If you are really comfortable and friendly with the GM, you can sometimes offer positively framed constructive critique, but this is a very tricky path to tread and you really need to have a strong trust relationship with that person.