They've upped the population for both modes a lot, so just sitting back and waiting for your opponent to exhaust themselves is risky. I think the best way to win in Skirmish is to constantly be building units - especially important right before you enter Dragon form. Hit the build troops button a ton so you'll end up with units. This is the hardest thing to remember. Once you secure a steady income, you must remember to spend it. If you find yourself with 1000 in the bank and there are still recruits on the map, you're probably on the verge of losing.
