If you are talking about marine gameplay, I would first keybind a hotkey to pick up your dropped weapon/item. Xeno gameplay involves stunlocking, so being able to immediately pick up your weapon instead of fumbling with your mouse is better.
If you are new, I would stick with one weapon with the most impact, which would be the m41a mk2. I am a full-auto believer ever since they nerfed the shit out of point blanking (pbing) xenos. You can try spriteclicking a xeno that is adjacent to you with burst-fire and then you realize half your clicks wont register as they put some stupid delay on pbing a xeno.
Luckily, it is pretty easy to make full auto viable for the m41a mk2 by either having a reflex sight or vertical grip. You can use a combination of reflex sight+angled grip for instant wielding, or magnetic harness+vertical grip for less risk of losing it. I always ask requisition for spare attachments, especially for reflex sight/magnetic harness and angled grip, as those get taken fast at squad preps.
For a short guide on full-auto, you pretty much hold down the mouse button and hover your cursor on the xeno while following it until its dead. If the xeno is right next to you, make a habit of holding down mouse button a couple tiles away then hover the cursor on the xeno (thanks for the tip @basilherbSG guide). Otherwise, if you hold down the button directly on the xeno adjacent you, you will only shoot them once.
Once you get gud, you can start carrying a secondary weapon such as the m37 shotgun with buckshot, which has insane value in being able to one shot pb runners and you can start stunlocking various t1/t2’s.
I wanna share my tactical and methodical way here … But I have a feeling that it gonna bite me in the ass and these Xenomorphic Being will try to counter it …
But here’s the gist of it;
"Don’t fear. Because the only thing they fear is You."
– John Marine, 2182
YES. You understand. Fear is the mind killer. Go forth and fear no darkness or the pain of death. Those demons must be defeated. Saint Michael and Saint George are with you.