I think I mainly just need to improve my speaking, since my reading, writing and listening are all pretty decent. But when I try to speak quickly I know I sometimes use the wrong tense or the wrong conjugation.
Anyway, I have decided to start learning German soon. I would much rather learn Italian or Spanish but it would make far more sense and be far more useful for me to learn German. I'm going to use the EXACT SAME self-taught method as I used for learning French as it worked really well for me. I'll be documenting it over on my Swiss blog.
Wish me Viel Glück! :)