Your thread title reminds me of this catchy tune lol 
Anyways, on topic. As far as having "too much free time" and wanting to utilize it, just increased your vocab comp whether by Core/Nayr/etc. If you do make your own deck, it is best to use the sources you delve into most like the anime and dramas you watch. You can do this by acquiring the subtitle files and putting through a word/kanji/difficulty frequency tool like cb's Japanese Text Analysis Tool. With that, you can prioritize which words you want to learn with this frequency tool. An alternative to yogert909's method which works on PC (and mac too I believe).
Erin's challenge is a good start. It is a mini drama/manga series (depending on how you want to go through each lesson) but I suggest doing both. Whichever order you want to do is fine. Then for manga reading, there is the Japanese in Anime & Manga site which is an interactive manga with audio, translations and cultural notes. Delvin language is a fun way to test your listening skills using real Japanese media clips (anime/drama/movies/commercials) which has N5-N1 levels.
Anyways, on topic. As far as having "too much free time" and wanting to utilize it, just increased your vocab comp whether by Core/Nayr/etc. If you do make your own deck, it is best to use the sources you delve into most like the anime and dramas you watch. You can do this by acquiring the subtitle files and putting through a word/kanji/difficulty frequency tool like cb's Japanese Text Analysis Tool. With that, you can prioritize which words you want to learn with this frequency tool. An alternative to yogert909's method which works on PC (and mac too I believe).
Erin's challenge is a good start. It is a mini drama/manga series (depending on how you want to go through each lesson) but I suggest doing both. Whichever order you want to do is fine. Then for manga reading, there is the Japanese in Anime & Manga site which is an interactive manga with audio, translations and cultural notes. Delvin language is a fun way to test your listening skills using real Japanese media clips (anime/drama/movies/commercials) which has N5-N1 levels.
Edited: 2016-05-20, 3:16 pm