Since you start at level three and with one thousand, three hundred and seventy five gold, So just grab your Hextech revolver, it will help early game and you'll get your boots REALLY fast. Start by harrassing with bouncing blade, throw and run, When you need to kill champions, and when you're ready to kill them (when they are about 25%) I'd Shun Po towards them, Bouncing blade, and they should die. when you get Death Lotus, combine it with your summoner spells to be able to keep them in it as long as possible. When using Death lotus, you can take them down at about half health, or maybe full. When you have a lot on shun Po, it's easy to keep up with them. (If you don't feel the need for Void Staff, Then buy a Gnashor's Tooth for the cooldowns. Just for the fun of it :D) Next to talk about is your boots. If you can see that you're Absolutely destroying them, Just buy Boots of Mobility, If the person you're going against has a lot of roots, and stuns, Buy the Mercury's treads.

you should be able to take out anyone in the game by now, Just watch your health, and don't get Ganked. In dominion, one of the main things is capturing points, but you must remember, killing also will take 2 health from their nexus. just go to the points where they aren't usually guarding, and attack them. Usually, you can take them without anyone knowing, and defend it for a while. If you don't feel like that, You can harrass down with Shun Po and Bouncing blade and then go in for the kill with Death Lotus. then take the turret down as fast as you can, Hoping that you don't take any damage from it. The object of the harass is to take as little damage from the Turret as possible, they have a STRONG bite. Just try to keep more points than them, kill them over and over and you should win.