English is not difficult to learn if you try several approaches at the same time. In fact, different people learn in different ways so try several methods before you choose what suits you: watching TV shows; doing exercises in internet; speaking to foreign friends; playing online games; writing on social sites.
Though not entirely chaotic, English is a language with few general rules so you need more than grammar and vocabulary to speak it. Classroom work is seldom enough and should be supplemented with other activities.
How to do that? Join groups at a business site like LinkedIn; subscribe to a magazine; watch films in their original version; plan a holiday in Canada; buy a Jamaican recipe book; eat at an Irish pub; visit a British food shop; start a blog; follow English politicians on Twitter; join a gospel choir; watch Premier League or NBA matches; surf through American websites; speak to tourists in your city; chat with your seat neighbour when you travel and try to meet foreigners with similar interests—for instance, to ski, visit museums or bike together.
Whatever it is, do it in English! This multiple approach will help you to learn fast both in and outside class.
Read more about how to learn business English at www.andymiles.com