No matter what language you are studying and what books you use, you will eventually need correspondence from a real speaker of the language. This is vital, as this person(s) can correct you, and teach you more
colloquial tricks to help you sound like a native. This native speaker of the language is also important for your oral and aural knowledge of the language. Learning to read and write a language is not always the hardest part. Learning to pronounce and understand the spoken language can be much harder, and these actually are the more useful skills. The internet is (again!) a valuable resource,look for a language partner ,a suitable one with whom speaking and practicing is worthwhile.
Now you need to keep on practicing and learning. There is almost always something new you can learn, and there is almost always some way in which you can improve. Ideally, you'll want to travel to a place where your new language is spoken. This is the best way to achieve fluency, as you are forced to constantly use the language. Eventually it will just come naturally. In the meantime, resume studying grammar and learn the remaining difficult and less common concepts, and always work on your vocabulary.