1) A lot of the principals from strategy casing still apply
2) You really need to understand your econ topics. You should expect a lot more technically challenging content (strategy consulting is more "soft" and brainstorm-y, econ consulting is much more "hard" and founded on scientific principals).
Make sure you understand key economic concepts + terms. I.e. Derivatives, Elasticity of Demand/Supply, GDP = CIGX, Nominal vs real (GDP, interest rates, etc),real interest rate formula (incorporating inflation), Unemployment rate/calculation (incl workforce participation), money multiplier, etc. etc.