How to become a better leader
Guides are almost always a work of personal opinions and thus results may differ.
Pretext
Being a good leader can be quite difficult - and usually also requires some out-of-game personality traits or skills. That being said, you can still implement various tips to improve your leadership.
Sound confident
Whatever you say - sound confident. If you're not sure rushing the enemy is a good idea, but it is what you want to do - just confidently say 'RUSH!'. Sounding insecure, will make people second-guess your decision. And instead of your full team rushing the enemy and potentially killing them, what usually happens is that some people will rush (because that was your command after all), while others will stay in position, as they heard your hesitancy.
Be personal
Instead of saying 'Someone please heal up this Person' - start by addressing people directly. Whenever you use the words 'Someone, Anyone, Somebody' and similare synonyms, usually what happens is that no-one feels responsible for your callout - and thus no-one bothers to follow it, because 'someone else will do it'. Instead, give direct commands to people. 'Zmeja, go heal Pyra!' would be a much better call out, as now, Zmeja is directly responsible for the task, resulting in a much higher chance of it actually being executed. Zmeja still has the option to tell you that he does not have medicine on him, for example - at which point you are still able to assign someone else.
Accept your mistakes
You will lead your squad to death multiple times. First of all - understand that this is not always your fault. Alas, oftentimes it still is. In those cases, understand that everyone is learning, including yourself. Your squad should understand that you are doing your best - and most likely, no-one could have done better. People who blame you, often do so after the fight. They might say things like 'we should have done that' - and while it might be good advice, a lot of people use that to actively demotivate you and try to assert themselves as 'knowing it better'. The old saying goes like: 'You always know better afterwards'. And this is most likely no different. Out of 10 people, almost every time in every scenario, someone has the solutive answer to the problem. But it is rarely the same one. To sum it up. This is a bias. When you succeed a fight, people with a different idea don't know their different idea might have failed, or they might even think it would still have been better. But once you fail, they think their idea was better. In other words, their ideas are 'always' better, however, this is of course not true. Should this behaviour take overhand, either mute those individuals, or make them lead the squad themselves for a while, so they can see how difficult it can be. Leading a Squad is hard. Not feeling demotivated and responsible after failing to lead one to victory, even harder. If some squad-members do not understand this - they are actively hindering your growth as a leader. Deal with them as you think is necessarry.
Marks
People knowing me, know that I am a fanatical fan of the marking-system ingame. I use it perhaps a little bit too much. And while that might be true, I see leaders not utilizing it at all! Marks can be used in a variety of ways. Marking positions to smoke. Marking enemy locations. Marking gathering points. Marking teammates in need. You might not need to use each and every option, but at least use some options to keep it lightweight - but still effective!
Assign a co-leader
This can be someone who wants to become a leader - or someone with a lot of Perception on his character in-game (usually a sniper). This is vital to success, as there will be times where you will die, at which point you lose your vision. The moment you die, it is of upmost importance that someone else will resume command! Otherwise, your squad will start spreading out and getting picked off one by one without any lead. Personal opinion: Don't forget. A bad plan is better then no plan at all!.
If no co-leader has been assigned and you die, try to tell someone directly to resume command! This doesn't always work, as people usually do not like to lead, but it is realisticly the only option you have at that point.
Perception
Your character should have a high amount of perception, in order to stay out of harms way and still see a lot of the battlefield around you.
Also, do not be discuraged to not actively participate in battle. When I lead, I rarely shoot. I am so busy giving callouts and moving around, that I simply do not have the mental capacity to do other tasks. That is fine, for the most part. Of course there are situations where you should utilize every single bit of damage you can help out with. Or help out a teammate. But you should still focus on your primary objective of leading your team to victory.