If you’re familiar with the MOBA genre (DoTA, LOL), knowledge from those games will transfer over well. If not, here’s a crash course:
Staying Alive over Scoring Kills - Like any other MOBA, this game is less about racking up kills on the opposition as it is keeping your team alive and making progress on the objective. If you find yourself in danger but you think you can clinch that kill while dying yourself - DON’T. Possibly the only situation where this is in your team’s favor is if it is to eliminate the only opposing healer character (and you yourself are not your own team’s healer). Dying not only leaves your team down a player for upwards of 10 seconds (often much longer), but rewards the opposing team with experience for the kill that will only make them stronger. Focus on keeping yourself alive, and once you’re confident in your limits, do what you can to keep your teammates alive when they find themselves in danger.
CC or Crowd Control - Any ability which hinders opposing players from controlling their characters as they normally would, or keeps crowds of AI enemies from overwhelming your team. These include Stuns, Slows, Knockup, Blinds, and Pulls. Keep an eye out for these effects on character skills if you’re looking over each one to see what they’re capable of - right now, skills with strong CCs dictate the meta. They are what allow a team to create a situation where there is no escape for a target before it is too late, and secure an important kill.
Managing Resources - You need to keep in your head, during all the action, a couple of limited resources that your team and your individual character need to stay in the fight and win. Starting with Shards, which are simple. It’s just a currency used to activate the gear items you’ve chosen for the match, or to purchase buildables on the map like turrets, healing stations, and giant minions. You find these scattered throughout the map, so as you make your way around get in the habit of running over them/shooting the really big ones. They spawn periodically, the little ones more often than the larger, so check back on areas that have several nearby each other often to keep a steady income going. Try not to be too greedy with the really big ones though, they show up only every couple of minutes, let your teammates have the chance to get some as well (but try and take them away before the other team can if they can reach them). Experience is the next one, which is more complex. You can experience directly from killing enemies, obviously, including the little minions marching around the map. However, you can get experience (quite a bit of it) from a number of other sources. You can also get a share of experience from Assists, where so long as you dealt damage to an enemy that was killed or provide healing to a player that did so, you will earn exp. Buying buildables is probably one of the best sources, particularly turrets. You will receive a bit of experience simply for purchasing/upgrading the buildable, but in the case of turrets and healing stations you also receive experience for kills and assists where those buildables for a factor. Turret zaps a minion to death? Counts as a kill for you, exp earned. Teammate kills another player while being healed by one of your healing stations? Assist experience for you! You can earn exp while not even being around or even alive thanks to buildables. The sooner you figure this out and put it to your advantage, the better. Because if you and your team can’t keep up with the opposition in levels, the less opportunities you’ll have to try and catch up. They’ll keep you dead or running too often to kill or build anything.
Play the Objective - That last one was a bit long, wasn’t it? Sorry, this one’s short. It may seem obvious, but I can’t avoid restating the importance of playing for the objective. It can even sometimes override the first point of keeping yourself alive. After all, if the clock is ticking down to 0 and you have the opportunity to put some damage on the Sentry or stop those last few minions from getting into the grinder and turning the score over, who cares if you die doing it? The main point is, don’t get distracting chasing glory and kills. Keep the enemy minions dead and your own alive.
Hope there’s some useful information for you even if you know how MOBAs operate.