This guide will show a few champions I've played, seen played, and watched own with impunity. These I have seen with my very eyes and learned from them, these I have played with my very hands and pwned with them, and these I will not only show, but improve with your comments/recommendations. And lastly, when Season 2 Masteries/Spells come out, this will be subject to changes.
These champions are all aggressive, and are good at it, and I ~will~ add more. You can recommend champions to me by leaving a comment.
Now without further ado, here it is.

Epic Champions

I happened to notice that not many people play Graves at all, which surprises me because I know his wonderful potential.
First of all, his main stats are attack speed and attack damage.
[*] Why attack speed and damage?
Well, let's look at the numbers. If you follow this build, then at level 18, you'll have 299.46 damage, and you will have a quick and easy 2.5 attacks per second. That's 748.65 damage per second. Meaning, if you focus someone for TWO SECONDS, that's 1497.3 damage, enough to kill a weak one and badly harm a tough one. This doesn't count your use of Buckshot, Smokescreen, or your allies. This does include Quick Draw, because it helps reach 2.5 aps.
So, that is near-instant death for those who challenge Graves.
Need I say more? I will anyway.
Your best skill is, in fact, NOT Buckshot. Nope, Quick Draw is where it's at. That short dash can help to step closer to fire a Buckshot, step closer to punish someone with your increased attack speed, a mere step to the side to deal faster damage to a turret, a dash backwards to get some distance from melee attackers and punish them, dodge skillshots, dodge Rammus...
The list goes on. A simple dash and improved attack speed goes a long, long way.
Buckshot is still the best skill to get first though, as it is a great farming tool, and it can harass your enemy laner rather well. Fun, amirite?
Now about Smokescreen. This ability can do wonders for setting traps, escaping, or unexpectedly getting a major gank out, not to mention its usefulness in teamfights. See, in teamfights, you can single out the damage dealer from the rest of his team, so you can annihilate without pesky Akalis, Talons, or Xin Zhaos getting in your way. Also good against Shen, Twisted Fate, and Nocturne, to keep them 'in the dark' (literally) when there is a team fight underway.
To wrap it up and move to the next champion, Summoner Spells and gameplay.
I take Exhaust to keep those pesky fast-movers like Teemo from escaping, or to hinder damage dealers. I take Ignite, so the damage just keeps on going when I can't chase.
For gameplay, I can mid, but I personally like to got top or bot. More enemies = more money. When you play Graves early, know that you are NOT superman, you are NOT the flash, and you most certainly aren't invincible just because you follow my guide. Play it safe, don't run around enemy towers like a moron, and if you're being engaged by a low-damage tank while attacking a tower, FOR THE LOVE OF GOD, don't shoot him or face the turret's wrath!

This is subject to change with constructive feedback, and will change anyway when season 2 Masteries/Spells get here.
Thank you, and please give comments and feedback.

This is my bro-champ. My brother plays him extremely well, and I mean EXTREMELY well. If at the end of the game, your team has 40 kills, Twitch got 35 of them. I am serious.
Anyway, I got his build mostly correct, but his skill isn't just his stuff, it's his gameplay.
He does a fair bit of scouting for singled-out champions and, if he can't kill them on his own, he calls on his allies to set up a gank.
He always goes bot and spends most of his time invisible. Not because he's a coward, but because he's looking for a victim. I don't spend much time looking over his shoulder, but from what I can tell, this is how he plays:
First, he goes bot. If there is someone in the brush, he starts shooting. Second, he farms minions. If someone steps too close, he starts shooting. Third, he pushes the tower. If someone gets brave, guess what? He starts shooting. Then he stealths away before he dies. When his tower is broken, he starts his 'hunting' phase.
He keeps an eye on his map to check for his partners, to see if they are in trouble. He deals with that, and then looks for free kill opportunities. He spends most of his time focusing on killing champions, and when there is nobody to kill, he pushes a tower. But as soon as an enemy shows up, he stealths to get behind him and starts hitting him with Debilitating Poison. If they get the chance to run, then he uses Expunge to finish his enemy off.
Now, in closing, he is at his finest in teamfights. When one goes down, he stealths to get in a positions that they are all lined up in front of him. Then he switches on Spray and Pray and listens to the music of a pentakill.

So yeah, that's how he plays. This is subject to change with constructive feedback, and will change anyway when Season 2 Masteries/Spells get here.
Thank you, and please give comments and feedback.
By the way, Gangsta Twitch skin. Epic.