Call of Duty: Black Ops III

Level 55 takes a little more determination, but to quickly reach Level 10 I would recommend playing objective game modes. If you're playing the objective (capture points, flags, etc) and you're on the winning team, you can average 2000 bonus XP per game on Core and even 3000 bonus XP on Hardcore. Pay attention to the challenges for your specialists and weapons and take a look at the Barracks to see what other challenges you can do next to earn XP. Play Domination or Capture the Flag and stick to the objective. Know the maps well enough that if you're separated from your team, you won't just be a straggler for the other team to pick off, and so you won't be following teammates out of necessity rather than strategy. Even if you have a poor K/D ratio, as long as you're good at playing your objective, you're going to hit Level 10 in no time. There's not a lot that can really be said about this one, but the other solution is a little vague so I thought I'd share my experience hitting Level 10.