I took one graduate level Macro economics class at GMU before venturing on to math and education. The math in economics is pretty brutal, even for those that are good at math. It’s different than a math class, a lot of optimization and a small amount of calculus/algebra that you use over and over again but must figure out when to apply it. My calc textbook wasn’t useful for this; it was Schaum's Outline Introduction to Mathematical Economics and a good calculator that will get you through the class (here). They also offer one for econometrics but it's not as useful IMO
Read until you have something to write...Write until you have nothing to write...when you have nothing to write, read...read until you have something to write...Jeremiah
I haven't actually found the maths in economics to be too hard so far(it's definitely a step down from undergrad physics, in fact I think I'm worse at maths now than before I finished my degree), though to be fair I'm not quite at the graduate level. If you have a mathematical background, Chiang is not a bad place to start I've heard. From glancing at it myself, I do like its structure. Also, for graduate micro there's Varian's Microeconomic Analysis, and the macro text for my current course is Williamson's Macroeconomics.
"When the King is far the people are happy." Chinese proverb
For Alexander Zinoviev and the free market there is a shared delight:
"Where there are problems there is life."