Here're some general advice. You're learning a skill in language, not about a language, and mastery requires practice. Your brain, swamped by stimulation, discards what is not put to use, so the more you use something, the faster and better you handle it. Memorize not only vocabulary, but also useful formulas you can rely on to get things done. Figure out what works for you and practice things yourself.
Consistent attendance is vital in a language class.
When you're absent, you've not missed a lecture you can make up by borrowing others' notes, but a unique personal opportunity to practice communicative skills that will be tested on exams. Assume that grammar does mean something . But in other languages, form and endings of words can make a huge difference in meaning, and you should assume that if a language has kept a piece of machinery for hundreds of years, it's because it communicates something and makes a difference. Be willing to take risks and make mistakes, trying out the new structures and vocabulary you're learning. At the same time, learn from your mistakes .