Destiny's Trials of Osiris is a very competitive PVP mode with great rewards; if you can overcome it. Having gone flawless over 50 times I have learned a lot about what to do, and what NOT to do. Here is a quick guide from what I've learned that can help you succeed in the TRIALS.
Trials of Osiris demands teamwork. It is important to stay together or at least know where your teammates are on the map. Coordinating attacks and switching off who is putting pressure on the other team will help your team to win. Knowing your team's collective strengths and weaknesses, and playing the map accordingly will give you the advantage. Communication is key.
Trials is a numbers game. If your team has less people in play, you are at a disadvantage. If you can't do anything else, get the revives. It is important to know how to revive as well. If the ghost of your teammate is being camped by a sniper, then you have to revive carefully and make sure to run into them as you revive them so that they get pushed out of the sniper's scope. Communication is key.
Knowledge is your friend. Before your team spends coins on buffing their Trials Passage make sure that you know the map for the week. When your team is flying to the planet, inspect the other team so that you know their load outs. Check what subclass they are so that you can watch out for their supers, and pay attention to their secondary weapon so you know how many snipers or shotguns to watch out for. Communication is key.
Be smart about where on the map you and your teammates are, and don't run out into the open without support. Every death counts, and so knowing where you are when you're dead is just as important as knowing where you are when you're alive. Watch for their team. Watch the radar for red, and be wary of the sniper lanes. Even if you are down you can still be a set of eyes for your teammates. Communication is key.
Trials can be very frustrating, especially when you lose near the end of your passage, or if you feel like the other teams are getting lucky wins or lagging. It is important to keep your teams morale up, and remember to have fun. Laughing will help you and your team feel better about the game, even if you are losing. Make sure you don't get so caught up in the competitiveness of the game that you can't enjoy playing it. Communication is key.
Shout Outs/Call Outs
Communication is key. If you aren't talking to your team, you're losing. You have to work together by talking about everything. You have to tell your team when and where you are down, and if your revive is safe. You have to talk to each other about the other team's weapons and supers so you can all know what to watch for. You have to shout out where you are going and where you see the other team so that your whole team knows how to react, and where to go. You have to work together by communicating what ways your team works best and how you can play to each other's strengths. Listen to your teammate's call outs, don't just focus on yourself. Remember that the most important part of communication is listening.