Starting area
There are up to 4 directions that can sprout from the starting area, and a good strategy to clear these areas without getting lost or eliminated is to take them one at a time. (Clear top branch, go back to the spawn area, clear left branch, go back to the spawn area, clear right branch, e.t.c)
Enemies
A good way to kill enemies without taking too much damage is to focus on enemies with ranged attacks first, and then kill the melee enemies. This helps avoid being knocked into traps or other enemies by a random projectile while in combat and makes the farming way easier.
Keys
Key spawns are VERY random, so it's very hard to give good tips on how to find them. They can be grouped up or spread super far apart. Use the branch strategy to help find keys, if one or more branches are clear, you will know that there are no keys left in said area.
Crystals
Max is 40 per world. Use branch strategy to collect all 40. Same method as keys.
Surviving
Get a cheap pair of Wings and a Claymore or Short Sword and with a little bit of brain capacity you should be able to make it through just fine.
Teamwork
You and your 2 teammates should either power through one branch at a time, or split up among the branches, slowly but steadily clearing all at once. Either strategy works, but the power through strategy is best.
Tips & Tricks
If you are standing on an edge of a non-harmful block, far enough where your character's feet are barely on the block but still on the block, any melee enemies will not be able to hurt, if u get hit you get a very short amount of time that you are unable to get hurt meaning u can get hit by a weak enemy than bypass a much stronger enemy meaning you can take less damage to go passed a couple of enemies in your way of winning.
Speedrunning
If you see the exit portal when entering the nether, leave before the game starts because having the portal at spawn is a big waste of time and there will always be another room, hallway, passage, etc. when u enter besides the door or room etc. that you came through. This will increase backtracking
Feel free to add more good strategies if you know them, it would be cool if this post could help some new players out that aren't into farming blocks, like me. Good luck!