Teammates
When choosing roles it might be wise to favor flexibility over damage. Teammates might not always be nearby or in a position to help.
In team-based games stay together. It might be wise to fan out in order to better scout an area or collect loot. Never go a farther distance than you can cover in case of surprise.
Teamwork
Always communicate enemy positions before or during the start of any other action.
Always call out items your teammates might find useful. Allowing a reliable teammate access to the items they can better utilize might warrant not taking them for yourself.
Always communicate your needs clearly and only when teammates are not otherwise engaged unless an emergency.
Priorities
When all threats are eliminated or otherwise gone it is important to heal before looting. One exception to this is assisting very close teammates for more overall firepower and allowing everyone to heal thus once saving time.
It might be wise to let an enemy wander into a more open area with less cover before engaging on first sight. This way you can get a few shots in without worrying about an enemy in cover who knows your position.
[Apex Legends] It might be preferable to pick up lower level shields than you already have since that will be faster. Even if you have a supply of energy tanks it still might be a better idea to keep those in reserve. Keep in mind lower levels of shield will permanently lower your maximum shield levels until you can find a higher level shield but a small amount is better than no amount on uncertain ground or with limited time.
Advanced
If two or more teams are in combat it might be wise to let them weaken each other before you engage. There is no point in making things harder for yourself. Make sure to jump in before you lose your opportunity to score more kills.
Escape
It may not be possible to escape straight away during a fight. Although the odds are against you it may prove a slightly safer bet to continue fighting if there is no cover or clear route away.
Advanced
Twisting hallways can be of great aid to put some distance between you and a confused foe but is not a sure thing. Depending on the layout it might be wise to double back after some time if an enemy does not feel the need to look in the same place twice.
Healing
After a fight in which you took a lot of damage it is important to make sure the area is clear before doing anything else. If your health is already low you have better odds not trying to survive a surprise attack during some other action. However other actions, such as reviving a teammate, might prove to be more beneficial in the short term.
It is important to keep in mind that in most games their squad will be notified where their teammate fell and, thus, where you are.
Landing
It is often a good idea to wait and launch backwards. This way you can see what areas are free of enemies after the fact to give yourself enough time to properly arm after landing. Many players will often launch as soon as they are in range of their destination and this can easily be turned against them.
Advanced
Although difficult to effectively organize, it might be beneficial landing in a circle formation in order to surround an enemy. Once armed most routes of retreat could be cut off in this manner while closing in. This would also make it harder to come to an allies aid when the need arises.
Terrain
Ducking, sliding, or jumping will create a smaller and/or moving target for your enemy to aim at. Your enemy might expect you to in your last known stance (perhaps eye-level) instead so this might give you a moments advantage.
Coming from an angle not expected (especially above or below) could make for a good surprise attack.
Always be aware of your surroundings. When passing a hallway or similar area never assume it to be empty. If there is or is not a current known threat it is wise to already have your weapons trained on that area while passing. Remember to look up and down where necessary.
Moving into a new area should never be taken lightly. Especially one that is more likely to attract more players such as an area with more valuable loot. Staying mostly behind cover when moving into a new area will give you the option to stop at any time and do some preliminary scouting.
Do not linger in an area too long unless all entrances and exits are accounted for.
Advanced
A fake retreat can give your enemy a false sense of confidence. Nearby cover will give you a chance to get into position before they can close the distance. Hide, quickly turn, and be prepared for close range combat as you will mostly likely be on top of each other. Cover that allows for quick enemy flanking opportunities are not often good candidates for such tactics.
Movement
Head out of sight in one direction and quickly turn around. You will either take them by surprise from the back or be face-to-face with them as you were previously but this time by surprise. If you wait too long you will have your back to the enemy. The more space an enemy would have to run to flank you the better but too much and they may not try.
More often than not hug walls. Avoid wide-open spaces with no or little cover. None to a small amount of cover gives little to no flexibility for movement or escape if things go south.
Always try to limit the amount of area you can be flanked from.
Inventory
Inventory space is often limited. As such replacing a lower level item with a higher level one is a net gain.
Do not be afraid to discard a weapon when running low on ammunition. It is better to do less damage in the long run then do no damage before finishing off the enemy.
An empty space is a wasted space. Pick up ammunition you do not yet need which can always be discarded later.
Practice
It is important to be mindful of your own actions just as much as it is enemy tactics. An honest, self-imposed post-game analysis can help you avoid making the same mistakes more than once.
Range
It might not be wise to engage an enemy as soon as you see them. Always ask yourself if you can effectively do damage at this distance.
If you can greatly outrange them you might be able to finish them off before they realized what is happening. If you can not support a short range fight consider what happens if they quickly close the gap.
Explosives
Explosives are best in smaller areas where enemies have limited movement options.
It may go without saying but try to limit the time they have to react.
Explosives are not always practical to cause damage with and are often better for controlling the movement of enemies. Throwing a fused explosive to one side will force the enemy to move in the opposite direction, for example. This includes the perception of an area being limited so placing an enemy between an explosive and a wall or even small obstacle might be doubly effective. This tactic can be used to keep an escaping enemy from entering cover before they get there. Throw an explosive to where you do not want them to enter when they are getting close but before they enter.
Advanced
Run behind cover as if hiding or retreating, have enemy follow, throw a fused explosive at the ground where they can not see it until they turn the corner and are standing on top of it.
Panic
Most of the above can be used to induce panic in the enemy. This may cause their aim to falter or make them choose less than optimal cover.
Above all always keep your wits about you and focus. This will increase aim and make tactics second nature with some practice.
Downed
Finishing off a downed enemy might be more important than it seems. A revivable enemy might be an enemy you need to fight a second time.
When helping a fallen teammate make sure to scout the area first. This is damage often easily avoided.
Advanced
In games where enemies can be left in a recoverable state one might leave them there as bait for the rest of their team. If cover is available hiding close by may allow you to get the drop on them. If the game supports tagging of enemies this tactic might be much harder to pull off.