I've found that the best way to rack up many kills in a single match are in game types like CTF or Attrition. These game types can last for a long time and aren't necessarily dependant on pilot kills to end the game. In CTF you can play some good defense to rack them up or just go hunting while people are occupied with the flags. Attrition is good for using your titan, sweep out all the AI and then go hunting in the Titan. Utilize titan punch and whatever gun you can get the quickest, most accurate kills. For me it's the chain gun and cluster missile for clearing out buildings.