Important Things to Note:
This is a fairly short topic. Additionally, it only occasionally appears on the comprehensive exam, so it’s not a terrible idea to skip it if you’re pressed for time.
Landau theory is a simple trick for handling real-life situations that are too complicated for doing simple stat. mech. for. The methods are mathematically very simple and there’s not many different ways to do this stuff. It’s really not that bad once you understand it.
Where to learn:
Read Chapter 3 in Equilibrium Statistical Physics by Bergesen up to section 3.8.1 (you can find a PDF by googling for it). I’m not a huge fan of this textbook, but I haven’t found anything better yet for this topic.