Easiest way is to kill kobolds. One group always spawns in the forest area with the ruins and a bear. You can also kill bandits, but these are way too strong to kill alone. Only humanoids killed by the main character count, which means you have to do the last hit. Companions can still deal damage to them.
More kobold groups will spawn as you keep killing, making the entire process easier and faster. Keep in mind that killing humanoids gives you large mood penalty. Picking the psychopath trait removes this penalty, but you can also just use alcohol, drugs or do other mood raising activities. Once you have enough kills, Mr. white will appear near your hideout. You can't miss him.