It is very easy to quit at an early stage. I myself need to see some results to give me encouragement to continue. Most programs, classes and books focus mainly on grammar and on almost memorizing randomly selected vocabulary. Although this is a major part of mastering a language, the outcome for a beginner is not that rosy.
One needs to be able to first understand, then to somehow communicate one's intentions. The better you are at this the better you know the language.
I learned AAA that way, I used to know the grammar very well and I still can read in an incorrect accent and pronunciation and get some ideas. I am far away from claiming that I know AAA, as my comprehension and speaking skills are almost zero.
I learned FFF almost similarly by attending two language institutes. I got a good grasp of the language though by attending in a short-time complete immersion program. Yet I was not wise enough to focus more on the conversational part of the language.
I had a better understanding of what it really takes to learn a language when I tried to learn Esperanto and to improve my accent to naturalize my second language. I have started to learn III and I am going to put all my experience into it, in addition to what I learned from the books I mentioned earlier. Here is my plan for now:
A) have a basic understanding of the grammar
B) learn some essential phrases
C) Learn important verbs, pronouns, ...
D) Whatever word or phrase I learn, I must have heard it as a native speaker says it.
E) Wisely pick a language audio package and follow it. Do not be tied down in learning every word, rule ... Keep moving in a planned pace
After mastering this level you are a survivor and then can proceed to higher levels.