In agma.io, there are many strategies that you may find useful, from a strategy getting to the glorious and mouthwatering #1 spot, to saving up enough coins for that magical Wizard Hat.
Getting Big Quick
One of the quickest ways to get a good amount of mass is to split into a couple of pieces once you spawn, since you really have nothing to lose. However if you someone near you is already split into a lot of small pieces, you should try and split over to them once or twice to get some of their mass. Then, you may be able to eat the rest of them. Don't split into a bunch of pieces into them, because you just end up feeding them. Another cheap, but reliable way for getting big quick is to go and find a teammate.
A quick way to get mass on this server is to repeatedly press the space bar once you spawn. This way you'll get mass a whole lot quicker then just staying as one blob. Once you get maybe 300 mass, it might be a good idea to find a virus and wait for someone with a good amount of mass to come. In this server, it only takes on W (one mass shot) to shoot a virus. So, you can shoot a virus at them, split them, and eat them. However, beware of the other viruses in the area because they might shoot a virus at you. Once you get maybe top 5, or 3000 mass, you should make sure to have a little piece big enough to eat viruses to clean them out because someone might shoot one at you, or to be able to shoot a virus at someone from a different angle.
First off, if you're looking for coins, I definitely don't recommend Splitrun Paradise or Crazy, because they are always full with players and it's really hard to get coins. It's also really laggy on them. That's why I barely play those two. However, Popsplit is the second best place for coins because there's rarely ever more than 30 people, and the average I see is about 14 players when I'm on. So, to get big quick, start splitting up into a bunch of pieces as normal. Once you get enough mass, go and some viruses and eat them. Eventually you'll get big enough to start shooting viruses at other players. Then you can get some easy mass. Then it's time to find a good teammate. With a good teammate, it will be easy to rule the server.
There really is no strategy on this server, but I recommend that once you get about 5k mass, you split into four pieces at someone maybe half your size, because you should recombine pretty quickly at that mass doing that. Same thing goes for when you are even bigger than 20k, it's a pretty easy way to savage people.
The XY and EU Test Servers are pretty simple. Spawn, split, eat viruses, recombine. Get near someone with about the same amount of mass as you. Split into a bunch of pieces in any direction away from them, and try to get them to bite. Most of the time they will split into a couple of pieces after you. If they do, recombine and then eat them. Once you get above 10k mass, it will be petty easy to double split. After you hit 20k, it should be pretty easy to dominate by double splitting and splitting into a bunch of pieces and eating everything ad everyone in sight.
Virus Farm Servers
The strategy is pretty obvious, it's in the title. All you really do to get big is farm viruses. Just like in Agarioforums.net, it only takes one mass shot to shoot a virus, so you can repeatedly press the W key to shoot viruses while you eat them.
Getting Coins Quick
If you want to stash up on coins to buy your own custom skin, a wearable, or the 100 mass bots, you want to go to Agarioforums.net, because coins deposit about every 20 seconds on that server. The second best server for coin collecting is Popsplit Paradise, because it is usually the least populated server, has the gold cube that you can feed in return for coins, and the coins spawn about every 40 seconds on it. Being on Popsplit Paradise for the most of 5 days, I was able to reel in 550k coins, which is enough for your own custom skin.
Getting YouTube Worthy Footage
Some "pros" out there want to show the world their skills, but the struggle is recording something that people want to watch. Some people will just post a video to Agma.io's channel to complete task No.1, but it has to be a good video. If you want you video to be good, you should try popsplitting some big people, but remember you can only really do this on X-Test Server, XY-Test Server, X_EU Instant, Popsplit Paradise and Splitrun Paradise. The other servers are hard to do it on. To popsplit someone, wait till they're overlapping the virus eve a tiny bit, and then double split into them. You also have to remember that you have to split enough into them to make them big enough to split on the virus. Once they eat the virus, you should have already eaten most of them because magically one of your pieces should be in the middle of the other person. I'm just going to warn you though, it doesn't always work. Sometimes people know you are going to do that and then split away once and then eat you. You can also do some tricksplits with a teammate (I'm not very good at this). Also, using a good amount of bots (usually 80 bots or above), and dominating a server with them should get you some good views.