This is more than a list of tips than are real "solution":
Teammates: This sounds a bit obvious since it's an achievement which requires you to play in a team. However it is possible to do it with random players (how I did) but it's more stressful and if you're unlucky enough then you'll need some tries.
Communication: It's easier to communicate with people you already know but it's also helpful to ping and use callouts. It's easier to react to something you see right away rather than to search and then to react.
Also you should share your loot with others. You can look health and shield of your teammates up on the left top corner. If you have a heal ability use it near your friends. Teamwork makes the dream work!
Stick together: You should stick together instead of roaming through the map. Always stay together otherwise you or your teammate gets down and then finished off real quick since there are 4 players. On the other hand if you focus your fire on one enemy they'll get down real easy and quick. Try to finish them off while you can.
Mount: Use your mount wisely. If one uses it, everyone should. The smaller the circle gets the less you should use it since it's very loud and enemies could locate your footsteps much easier.
High ground and Indoor tactics: If you're able to get the high ground then get it asap! It's a huge advantage and a basic method to maintain overview throughout the map. You can also spot enemies easier and attack and crouch behind things while your team attacks from another side. If you can't get a high ground then don't try to stick to indoor. There are many abilities and weapons which have aoe damage and you might get caught inside the storm if you're fighting and not paying attention to it. Stick to walls, mountains and things like that but avoid flat landscapes since there is nothing to cover from. You and your team will be an easy target.
Ability and Runes: Yous should focus on getting runes early on. There are some runes which are very beneficial. There are some of them which give you bonus damage, healing bonuses, movement speed, lifesteal and more. Use your abilities at the right time! If someone is barricading himself inside a house? Use the one which bounces on the surface. You got hit and you're behind cover? Use your healing station and heal yourself with armor potions.
Feel free to leave a comment if you have tips I can add!
And please give me feedback before downvoting so I can adapt my "solution".