Level 29

Total Experience Required 120,435 [confirmed]

Level 100 progress: 1.76%

This is roughly:
Killing 402 people in Warzone, or...
Killing 410 people in Execution, or...
Killing 341 people in Wingman, or...
Scoring 86,025 points in Guardian, or...
Scoring 261,816 points in Annex, or...
Scoring 158,468 points in Submission.

Horde (TU4)

Completing 603 waves on Casual, or...
Completing 402 waves on Normal, or...
Completing 302 waves on Hardcore, or...
Completing 241 waves on Insane.

Or a combination of the above. Have fun!