You take lessons once a week? Your coach would be a good person to ask this question heh 
I'm not a coach, but if you want random opinions on the internet, broadly speaking I think of practice (for any skill) as falling into two groups. First is drills you do daily (to retain memory or form) and second is the difficult or new stuff you work on.
So going over your openings or technical endgames with only a board (nothing to prompt you) and see how much you remember. Or Tactics. These can be drills.
Analyzing tournament game(s), working through a book, solving really difficult studies or puzzles, this can be your main work.
Now to answer your question, IMO pick an area where you're weak or not very knowledgeable (like a particular endgame, attack on the castled king, exchange sacrifice, an opening, pretty much anything). And make that your topic for the month. Use books, databases, videos, to collect info. If you have a whole book on just that subject then you could just read that.
If you pick a specific opening, it's different from memory drills because now you're e.g. getting a collection of 10 or 20 games (ideally all from one GM who plays the opening often) and playing over them, asking yourself questions, analyzing for answers, not just memorizing.
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Anyway, that's my general take on improvement. Good luck.
I think i have repeated the same topic, but i'm 15 years old, 1500-1600 rated, and i'm trying to find a study plan to improve steadily, as i have tons of work for school. I recently almost beated a 2200 player (lost btw as i didn't have time on the clock), and that sparked my interest and my hopes becoming a master myself. How can i achieve that as soon as possible, without dropping out of school. I am recently doing as many tactics as i possibly can on ChessTempo ( in the summer i did almost 2000 tactics), learning openings from a site and Silman's excellent book (Complete Book Of Chess Strategy) (I recommend it undoubtedly), and endgames from the same book, and i'm trying to start reading Silman's Complete Endgame Course, as it gets deeper in endgame theory and knowledge i need to have if i want to become a master. I am registered in a chess club, i go for lessons there once a week. I take part in tournaments. How should i make my study plan? Let me know if you have any suggestions please in the comments.