We are all different, and therefore we struggle with certain areas more than others. A textbook doesn’t necessarily cover the areas where you struggle as much as you wish, but fortunately you can just make your own quiz covering these areas.
To inspire you in the right directed I have made some examples on how I use a “homemade” quiz.
Insert pictures and guess its name in German. You can also add 10-50-100 words every week or month and by no time extent your vocabulary significantly.
Record German tongue twisters and see if you can repeat correctly.
Make learning grammar less boring and more effective…
The possibilities are many. Remember to save your quizzes somewhere easily accessible, for instance on your desktop.