learning second language

In my opinion, the most important factor that affects proficiency of second language learning is when you start contact the english environment. That means the earlier start, the more proficiency you have. I think the more English people around you that makes you fully with the English in your mind and you talk more. Therefore that makes the person improve a lot especially in speaking.
However, I also thinking right now. The writing skill affects proficiency a lot. Each time, when I begin to write I always fell a little bit scare because I only have one chance to explain my ideas and sometimes the grammar mistake can make people misunderstand you especially in exam.