Very few people are still playing this legit. That said, the average game is 2 vs. 2, so being in the top three isn't as difficult as one may think. Stick together with your teammate(s) and get as many kills flag/objective captures as you can.
This can also be boosted relatively easily if you have a group of at least four people. Decide which team will win, and then allow them to be the only ones killing capping flags/objectives. They both will be in the top two on the score-sheet.