Listen to lots of podcasts that cover a wide variety of topics, I don't know what your level of listening is, Gerry talks slowly and clearly (maybe too slowly for you) and the written script is displayed on the page. Try listening and repeating to get your muscles accustomed to the flow of the language. Do language exchanges with native speakers as often as you can, practice, practice, practice, is the only way.

Find Gerry's podcasts here

http://www.podclub.ch/sendungen/gerry-s-news-digest-e

http://www.podclub.ch/sendungen/gerry-s-diary-english

And some from Owen Here

http://www.podclub.ch/sendungen/owen-in-china-english

Best of luck.

How can I speak English more fluently?

I've been studying English for many years, but I want to speak it more fluently and improve my vocabulary.

I agree that you need to speak more with native and advanced speakers, but please don't ignore the grammar! There's no point in learning more words if you just say them in a random order. :)

Treat the grammar as useful little structures which make your meaning absolutely clear. That's one way of making your speech fluent and pleasant to hear.

Make friends with people that can talk english. 
Watch some shows and study them

i think that the best form to have vocabulary and speak more fluent english is Singing, when you sing, You have to pronoun the words the form that the song and the voice join, moreover, its more funny.

But  talk with other person in english is a good idea!!!

I can help, maybe? 

I'd recommend watching more TV shows, reading books and finding a partner..you can really improve your conversational English that way.