Largely depends on your learning style and personality. I personally think Meteorology is a tough one. First of all because it's large en second because I find the theories incoherent.
Others have no problems at all with the MET subject but are having difficulties with Principles of Flight, Radio Navigation or Air Law because they can not see the "logic" of it.
By the way, General Navigation is based on a few basic principles. As said earlier, get very close friends with the Flight Computer and Bristol. Get to know the basic principles, i.e. high school geography plus the extras like Grid / Polar Stereo / Lambert / Mercator projection and related terms like constant of the cone, convergence.