What is the most tough part in learning english?

I'm interested to learn this language as my second language..
I read many articles, techblogs, online newpapers and comments..
I found that my vocabulary was too bad and so on my grammar..
I do ever tried to talk with others using these language and...
I am convinced that all of you should know what happend then..
So, please tell me what should i do before trying to talk with others using
this language...i am the person who look down to earth all the time!!!