Join a squad in the spawn menu. It's highly recommended to work with a squad. You can join and leave squads of your choice, provided they have openings. There's then a tab to select role. You are either a generic infantryman or you can choose to be medic, use light machine gun, etc, if there's space. For a start, you may want to just stick with being a rifleman. You can try out the other roles later, of course.

Do not be afraid to use your microphone. Make sure you tell your teammates if you see the enemy, or where you think the enemy is. For most of the games I go into, people are usually fairly nice, so unless your squad mates are jerks, don't be afraid to ask them questions.

Sometimes, you cannot identify where the enemy's location is exactly. It's much harder to find the enemy often times than to actually kill them after you've really spotted them. A lot of times, you try to fire in the general area of the enemy, or where you think the enemy is. if you have a good machine gunner on your squad, he/she will try to suppress the enemy, hopefully.

Use the bearings (numbers) on the compass to tell other players the direction of the enemy.

Try to stick with your squad leader. When using the e-tool shovel, left click is to construct / build and right click is to demolish, in case your squad leader asks you to build something.

Lobbing grenades is extremely good for hindering / killing the enemy. In one particular match I had, it became a dodgeball session in one objective and both teams kept going back and lobbing grenades over the wall(s). And we ended up with tons of kills, not even knowing.

If you're bleeding / injured (you will tell if your screen is sort of showing an "adrenaline" look), take out your field dressing and hold right click to patch it up. Get a medic's help if there's one nearby.

The controls are mostly pretty simple and you can always rebind the keys to whatever you feel comfortable with. The game is really not too complex once you play a couple matches and get the hang of it.

Of course, you want to aim and when aiming, holding shift sort of makes you focus / zoom in on the sight more.

When you're near an ammo crate, use it and select Resupply to stock up on ammo, just in case you happen to run low on ammo.

And seriously, very importantly, have fun!!!