So, since I'm one of the top killers and I've met and played with the top winners of EggWars, I noticed that we all use different strategies, and they depend of what map you are playing on, and their details. There are strategies that I don't know what they are called or how to call them, so I'll just use the names that I use :)
Rusher
Suggested map/s: TeaParty, Oriental and Dwarven
Kit: Healer
Island Location: Closest to middle
Good to farm: kills
This is the strategy that I use the most, and since I play a lot on the map TeaParty, I will explain how to use the strategy there (bare in mind that you can do the same in the other maps suggested by me).
So before you start the game, you would need to pick a team, and in the map TeaParty, there are 4 islands/teams that are close to the middle, green, orange, cyan and pink (I don't know which islands are closest to the middle in the maps Oriental and Dwarven, so you must find out for yourself). When you have chosen one of those islands/teams, the first thing you do, is get at least 35 iron at the start (the iron that is there when you drop down) to buy 60 blocks of sandstone, and a wooden sword. With those 60 blocks, you build to the middle as fast as you can. Once in the middle, you get as many diamonds as you will need (44 diamonds for full iron armor w/ diamond sword and a punch bow and arrows, or 1 stack and 12 diamonds for everything listed before, but with a notch apple included @SpyYoshiRv correct me if I'm wrong on the calculations :)
). Bare in mind that your golden apples of your healer kit will be your food and health boost when you are there. Once you have the diamonds, you go back to your island and buy the things listed above and you can kill anyone in that game since you are more op than the others :)
Wins
Suggested map/s: Rome
Kit: Rabbit
Island location: Any
Good to farm: wins
This strategy is more used for the top winners, and thanks to them I know how to do it and explain it. So, after you chose a team and the corresponding kit, and you are waiting to be dropped when the game starts, you need to go to the closest iron generator there is and collect the 'starting' iron. With that iron, you buy only blocks and begin building to the middle, but this time, you build the bridge by making a staircase so it is not reachable from the middle. Once you are on the middle, you go onto the enemy's bridge with the jump boost potion activated, and you brake their egg as soon as possible. Once their egg is gone, it doesn't really matter if you die because you still have an extreme advantage over the others since you have an egg while they don't. When that is done, all you need to concerntrate on is by killing the other team, which is easy because they will barely have anything since it is still 2-4 minutes in the game. (My record on this is 2:15 minutes on the map rome, thanks to the top winners :))
(This strategy works on every map, but I suggested Rome because it is the fastest one possible :p)
Airborne
Suggested map/s: Magic
Kit: Any
Island location: Any
Good to farm: nothing
This strategy comes in play when you are already in-game and you've just lost your egg. What you need to do, is gatherup as much blocks as possible (I suggest getting 4-6 stacks of blocks) and build up until you have used 50 blocks (more or less), then you begin to bridge over to an enemy island that still have an egg. Once you have bridged over, you might be wondering on how to get down without dieing, well, in the map Magic, at the top of the towers, there is some water where you can land on safely. I use that water to go down to the island and brake their egg, and eventually kill them all. Once you've done that, you swim back up to your bridge using the water, and from there, you bridge over to another enemy doing the same thing that you just did.
I hope this helped you in any way to become better at EggWars, and if you have other strategies, feel free to post them :)