This level is all about XP gathering, and I think most of the level speaks for itself. The little, but very valuable, tents throughout the level give me quite a lot of XP, so I'm destroying most of them if not all actually. I also upgrade the Trading Route so that it delivers XP quite a bit faster. Killing Outlaws all over the place also gives lots of XP, so I'm killing them all :) In order to capture Holme, you only need to destroy the Gattling Gun... So I use Cavalry since they have faster movement and are good at melee combat.