Speak, speak and speak! Practice everywhere. Dont be afraid to make mistakes. Watch movies and listen to radio. Make everything possible around you in that language

I think be live the language. Watch tv, ear sounds, talk about very diferents views points.

I think the most important part to be honest to not sounding foreign is to understand the grammar. Here in California there are many immigrants from Asia, for instance who are still learning English. It is very obvious just by the syntax and lack of proper suffixes that they use and immediately tells me that they are learning or have not fully learned the language. However, they can almost always be understood so as long as you can at least make some grammatical sense, the next most important thing is probably impeccable pronunciation. As for reaching any level of fluency, whatever method works best is the most important but for me, picture to word associations (in the style of Rosetta Stone) works very well. This is the way that we as children learn our native languages so it makes sense that the same formula would work for foreign ones.

live in a English speaking environment

Speak and lisen