wiifi, make sure you're holding the ASD notes down for their full duration, and that you're not hitting an extra key. Both can prevent you from getting perfect without actually decreasing your multiplier.
Ymbirtt, try muting the chat window. Not perfect, but it helps a lot. Also, if you've got other tabs open (especially an auto-refresher like GMail), close that while you play.
In Dire's defense, he was right about one thing: you can't see immunities before the level starts. Solution: focus on generalists. They do more damage anyway.
Popup700, new maps only I think. Says in the info that there are a set number of skill points you can earn, but you can always redistribute them.
Rainers, if flying units give you trouble, rely less on dexers and consider investing skill points in unlocking archers.
Card is bugged - over $129.99 in two separate game files, one of them in 8 days, still no card. Even have the lvl 10 badge in one file, which requires more than $129.99 in tips; still no card.
Horrendously tedious game. This is the type that would get reviewed--and subsequently (and justly) smashed--by the Angry Nintendo Nerd had it come out for the NES.