My biggest problem is the writing part, particularly with verbs. I never know if I should be using Perfect or Imperfect...
... "if I shoud be using Perfective
" is the right formulation and this difference is very imortant, though it may seem minor to many.
Personally, I would vote for the importance of listening (and speaking) compehension in learning a foreign language. That's what I did for learning English a long time ago. However, this exercize should be accompanied by memorizing the entire passages. Memorizing should be done from listening, not from reading, which means looking into the written text. It should be done systematically, but not too much volume at one go. When you master the passage, you may then try to write down what you've learned and what you've remebered. For the human mind, listening and speaking is much more intrinsic than reading and writing. The latter is the invention of culture, the former arises from our biology and evolution and was invented by Mother Nature. Repeating is essential for internalizing the foreign language.
For the last several years, I've been learning French mostly through reading and quite rarely through listening. When I went to France this year, I did get on well, but I was annoyed by not being able to formulate my sentences instantly and without the perfect rythm and intonation proper to the language. On my return to Poland, I decided to start learning French in a different way: I watch and listen to the news in French or French films just trying to concentrate on the rythm and intonation of the language, not even trying to understand what is being said. And imagine: words and meanings come to me by themselves; I begin to grasp the forms of words that I come across for the first time ever (later on, I check them in a French monolingual dictionary), all this without even trying to "hear" words or structures in the speech. All this seems to come up naturally and effortlessly when I am well "de-concentrated" on the meaning of the words and phrases being uttered.
In a year, I hope to build up a sufficient collection of words and phrases to be able to pick what I need of them in a given context instantly, without hesitation and with the rythm and intonation characteristic for a French sentence. Will I succeed? One never knows ...