As an ex high level CS player I disagree that adjustable DPI and weights are necessary things for mice, though for some people used to certain things (like a heavy old mouse or one with low sensitivity) they can provide some aid. That said, the G500 is an excellent mouse for all things PC and gaming, I have two myself.Some good general tips for people just starting (or still sucking) at FPS games. Being relaxed with shooting is really numero uno. Being stressed or anxious makes your aim go to crap, and you learn a lot more by playing in an analytic fashion.
You've read about Planetside 2, heard about all the epic battles. It all sounds amazing, like Saving Private Ryan crossed with a blood orgy taking place in the middle of a rave. And now you, an EVE player, someone without much an FPS background, wants to play Planetside 2. You're at a huge disadvantage, truth be told. FPS skills translate very well and your lack of background means even someone who just plays casual TF2 has a leg up on you. You are at the bottom of the food chain. Luckily for you there are lots of ways to fix this, and being new means there's still easy things you can do to make huge improvements that barely involve playing the game. This guide will come across as basic to anyone with a passing knowledge of FPSes and is more intended for people getting interested in PS2 without an FPS background.
First, we need to talk about mindset. You're bad. Get over it. In a game this large there is always someone better then you. You'll get caught offguard and killed in ways you didn't realize were possible thanks to Planetside 2's high lethality weapons. Just calm down, you'll respawn in 10 seconds. When you die ask yourself these three questions.
“What did I do poorly?”
“What did they do well?”
“What can I do to avoid that death in the future?”
On the flipside, while you're alive you need to be asking yourself.
“What goal I am trying to accomplish”
“Am I working towards this goal?”
“Is there anything I should be doing instead?”
Luckily, the zerg and/or your squad commander usually provides easy answers to the first question. The second and the third is a bit harder. For the second and third, just make sure you're doing something that actually supports your goal instead of sitting back sniping poorly (yes, you snipe poorly.)
Speaking of shooting, always shoot like you mean it. Don't panic, take your time and make sure you're going to hit your target. If there's not time to aim there's no way you're surviving anyway. Just relax, if you die you respawn in 10 seconds and one death in a huge battle means very little. This doesn't always mean ADS (aiming down sites). That really depends on the firearm. Some work fine from the hip, while ADS is mandatory at all ranges for others. Your basic default weapons are very much a generalist's tool and so will do reasonably well with aimed fire at any range and hip fire at short range. As you unlock new weapons, further specialization will be available to you based on your preference.
Another important matter is your mouse. It's your primary means for controlling your view of the world, interacting with it, and actually engaging in the business of shooting people. It's the area where you can easily make the greatest improvement. At minimum the mouse you use should have adjustable DPI, better yet, programmable buttons and weights. For right handed players I recommend the Logitech G500. It's 40 dollars and has absolutely everything you need. For the left handed I recommend the Razer Deathadder, one of the rare explicitly left handed gaming mice. It's not quite as excellent but will still serve left handed players well.
Next, we need to find your mouse's sensitivity. Get a ruler and put it against your mousepad, load up Planetside 2 and then simply stand at the warpgate. Pick up your mouse to avoid moving your character and put it on one end of the ruler. Now, turn your character 360 degrees. This is how most FPS players measure mouse sensitivity to make up for all the differences DPI, game options, company firmware and computer settings can make. Anything under a foot (about 30cm for the metric users) is too high for most people to make fine adjustments without overshooting. I personally have an 18 inch 360 but you should play around and see what works for you. Weights are something else to consider once you've got a good feeling for your mouse, if your mouse supports them. They're honestly a bit more subjective then sensitivity and you should experiment and find what works for you.
Now let's look at your control scheme. Just sit there and think about how your hands move when you play, put your fingers on your movement keys and think about how easy it is to press certain keys. Can you easily reach your sprint and crouch keys? How about the spot key? Melee attack and grenades? See how it feels just to press them and think if there's a better place to put them. Make sure you can reach all of your weapon selection keys. And put as much as you can on your mouse, I have my main weapon (LMG, AR, Carbine), melee weapon, and sidearm all on side buttons. Even more importantly, remember to use them. Your sidearm is surprisingly good and it's more effective to take it out then stand there reloading your primary weapon while your enemy sprays you. The knife is also an excellent weapon, it two shot kills any class but a MAX suit, is completely silent, and doesn't reveal you on the minimap. It's hilarious for ambushes and often trumps firearms at the most extreme close range combat.
Most importantly, you've got to realize it's a journey. If you meet Gosu on the road, turn his brains into avant garde splatter art. There's always something to improve, and losing is the greatest opportunity to learn because it shows you a new challenge. You screwed up, probably without realizing it, but in a scant 10 seconds you get a chance to put what you learned into practice. It's a great big adventure (that happens to kill thousands of people) so go have fun!