Average level players can also remember all of the Kings played in addition to the Aces. They are also much better bidders. They'll look at how many cards they have in each suit and take that into account when bidding. Expert level players can do all the things Average players can do, but they can remember every card played, not just the previous couple of tricks. This elephant-like memory makes Expert level players formidable, but it gets worse.
Experts also count the number of Spades that have been played.
They also remember which suits other players have trumped and they'll take that into account when playing a card. You can use the Risk Levels of your opponents to influence a variety of things, from how high they'll bid, to the possibility of trumping when they have the chance. But, keep in mind that an aggressive player tends to be a bit cocky, and conservative players tend to be a bit timid. With a new baby in the house, it's been challenging finding the time to balance everything. I don't think either of us ever imagined it'd take this long to get 1.0 out the door.