If you want to learn a language other than English, you should consider learning Spanish, French, Russian or Mandarin instead of German if you're not planning to study and/or live, work in a German speaking country. A friend of mine is a student in Freiburg, he's studying the German language, he said, if your L1 is not German, then you'll never truly master German as the infamous articles in German are more of a feel thing rather than rules. I'm told that, conjugations in German don't always match with the Turkish conjugations, for example the subject is Dativ in German, it might be Akkusativ in Turkish vice versa. If you like the language, or you have a reason similar to the or the same the aforementioned reasons, German is not that bad of a choice. It's not a bad choice in general either, it's just harder than other Germanic languages and Romance languages such as English, French, Dutch and Italian. If you want to learn German better, maybe you should consider attending the Goethe-Institut school.