Also for beginners, who noticed they have no building spot for the catapult factory. Go for the southwest castle; it only requires frontline units to attack it and it'll give you that building spot. BONUS - if you can resist, do NOT build an alchemy bldg as your first; instead save that spot for a market, and the next spot you get for the eventual catapult plans (You won't need alchemist for awhile anyway). DOUBLE BONUS - if you follow the bonus advice, you can attack the east castle first - you still get the dialog 'Well, you beat the guardian of the West...'
also useful is to have a any-lane card (e.g. quack or motorcycle) in the back row with an artillery piece on it. Use it to snipe down any of those invis snipers
Want to add me to the list of your negs? Fan? I (used to) rave about this game on other sites - my 3 accts combined would put me in top 75 for alltime gm wins. But this new economy - blechh. Would hate to be a new user now (and game DOES die without new users). Shop is now boring; the lowered experience gains for common/uncommon are very hurtful; too easy to make wrong and unrectifiable decisions regarding card upgrades. Two thumbs down.