I don't know how to help you. I live in the states, though not a qualified teacher by any means, below is some of my advice if you don't have years to devote, and don't already live in an English environment.
There isn't much point in learning to write when the main objective is to communicate through words. Perhaps start by saying everything you would in a normal day in English. Then learn sentences that may come in handy when communicating with a client.
For me, when I work with a client, the most important thing is listening and then giving a solution to what their problem is. Hope the above information may be of use!