Great article on pull-ups, useful for beginners (although it calls them chin-ups). Overhand grip is pull-ups .underhand is chin-ups (where I come from! One of the best compound exercises for building muscle, strength and mass.
NO EXCUSES! Home workout [Note to self: add 1 min plank to rotation and instead of burpees do mountain climbers and/or spiderman crawls). No excuses. Even if the day is hectic at least do this exercise at home