I want to reduce my grammar ?
You don't want to reduce your grammar (and that is not a question). As you said in your title, you want to reduce your grammatical mistakes. The simple answer is practice. Reading is great but you need to speak as much as possible, preferably with native speakers. If there is a language exchange group where you live, then join it. There are some websites where you can chat with people by Skype too. Listen to English radio, watch English TV etc as often as possible.
I used to read many books but when I'm using English in real life, [STRIKE]I'm not getting[/STRIKE] I don't get it right.
I don't think you mean "I used to read many books" - that means you read books in the past but now you do not read many books. Perhaps you meant "I am used to reading many books" - reading is something you do frequently. As I said above, reading is great for vocabulary and general practice, but they won't help your spoken English.