Spaced repetition

• Software: Anki

Works for vocabulary acquisition and memorization of idioms, fixed grammatical structures and sample sentences.

During class

• Keep a separate journal/scheduler for each language (a thin, small, plain notebook works beautifully). Each class, write vocabulary on the left page, note down important notions on the right one. Leave a small separate space at the bottom of the page to write down homework assignments. Use a tag list at the last page of the notebook if needed, such as here. Use last pages for special sections you may need such as average calculation or important data (teacher e-mail, whatever). If you need even more structure look into methods such as the bullet journal. This notebook doesn't have to look neat because the nature of the information included (homework, new vocabulary) is ephemeral if properly stored elsewhere, but be fancy about it by all means if it floats your boat.
• Each day or every few days, input the new vocabulary you wrote on your notebook into a SRS such as Anki. This is going to save you time and misery when exams time comes.
• Print Cornell paper and use the hell out of it. How you use it is up to you, but it always tends to make things much tidier and allow for note drafts that serve as definitive revision texts when studying for the exam.

Vocabulary accquisition

• If you've got a Kindle: download the integrated dictionary for the language you're learning, make all the notes you need and look up all the terms you don't know, then review directly from the device or by use of tools such as this one.
• Book outliners are your best friend. This one from David Seah is just beautiful.
• Software and webapps: Anki, Memrise, Duolingo

Writing proficiency

• Lang-8
• Sample phrases: tatoeba.org

The cheatsheet

• Try to fit in a sheet of paper as many of the concepts that you need to revise or work on as you can. This way you can revise only those bits of the language you need until you familiarize yourself with them.

tbc...