Instead of taking lessons, they are expensive and often based on old-fashioned methods of teaching, I would advise you to use a combination of textbooks and getting help from a helpful native speaker online.
All the questions you may have after reading a text can simply be addressed to this person.
Few would do this free, naturally, but you can repay their kindness by helping them to learn your native language. The phenomenon is called language exchange and it’s getting increasingly popular. You can read more about the phenomenon in my article Finding a German Tutor Online.
My language exchange mates have also been willing to listen to me reading out from a textbook and often helped me to correct written grammar exercises. I’m sure your German tutor would be happy to do the same for you, as long as you are willing to help your tutor with the same enthusiasm.
How to I find myself a good textbook?
Before anything else, you need a book that suits your level of German. Are you a completely green, do you know a little, but not much, or are you getting quite intermediate?
Moreover, I will suggest considering some personal preferences. It may not be the end of the world to read textbooks made for high school students, but since there are textbooks made for different age groups and other preferences, why settle for something else?
A way to find a good textbook is to go to a library or a bookstore and pick your favourite from their assortment. Very few libraries and psychical bookstores have a proper selection of German textbooks, though. Therefore, you probably need to look for one online:
Amazon.com – German Language Instructions
The great thing about Amazon is the many reviews. These reviews can help you to find a good quality textbook with the right level of German.
Vistawide is a language source database. They have made an overview of textbooks sorted by level with a short description to each of them.
Learn German Online do not only link to textbooks they recommend, but they do also link to publishers, which publishes German textbooks.
Where should I buy my textbook?
As said before books on learning German are not very mainstream. For this reason, you will most likely need to order online to get exactly the one you wish to buy.
Amazon has the biggest selection of books in the world, and they deliver to most of the globe for relatively fair prices.
Alternatively, the internet directory Dmoz.org have a list of bookstores and if you scroll down you can choose your language to find local alternatives to Amazon.
If neither Dmoz and Amazon have the book, you are looking for, try Googling the book title. Usually some online bookstore have it or someone is selling it used.