Oh well, I don't like these RP games but just for this time, I'll indulge myself.
I would be a brown coated, black-maned Earth Pony with a notepad as my buttmark because I have this habit of taking notes for everything IRL. (It's useful, actually.)
I would work from 9 to 5 at the Mayor's Hall taking care of the town's registry, keeping dates, numbers and important stuff safe and available for whatever official use the Mayor would have for them. Good job, good pay, drinks and pastries delivered by Pinkie Pie twice a day and nice respect from my co-workers, but the monotony of the job tends to be annoying.
My best buds would be:
Compass, a blue and white pegasus with a compass buttmark, who works as part of Ponyville's weather patrol and also works part-time by making deliveries at the postal office. Unfortunately, Compass's orientation sense is subpar, so he can't handle long trips without risking getting lost for hours: in one ocassion he challenged RainbowDash to a race, but he couldn't find the goal and Rainbow defeated him with ease. Since then he considers her as his rival and trains to hone his orientation instincts, but by when he finally could challenge RainbowDash for a rematch, the girl most probably will have completely forgotten about him. (Talk about anticlimatic outcomes)