All of their concepts are appropriate. For me, the idea of voluntary trade being a positive-sum transaction (and not a winner-loser transaction) is tops for me. Once you accept that, I believe your whole economic world view changes for the better.
I encourage you to check out the links in Roth's post above - interesting stuff. Of course, I had to throw in mine. Here they are:
- The understanding of wealth transfer vs. wealth creation, and that the latter is applicable to the real world.
- Comparative advantage and the benefits of free trade.
- Elasticity of Demand and its relationship to increase in price (especially artificial increases due to tax policy).
Honorable mention: What I call "The Laffer Effect" - finding the optimal point on the curve (tax rate) to maximize revenues to a treasury.
Its debatable whether or not items 1 and 2 are prioritized correctly. A rejection of Zero Sum economics cannot be overstated, in my opinion. Its ignorance of the first point that continues to empower a certain political party through class envy, that's why I kept it at number one.
Apologies to any of you hard core economists for my novice input.....