If you don't have much opportunity to practise, it can be difficult. I learnt Portuguese when I lived there and haven't used it in years. To keep it alive I try to have imaginary conversations in my head so that I don't forget it. Someone once suggested to me that trying imaginary interviews was a good way. Also, listen to as much as you can. If you have access to stellite TV, then watch programs like chat shows and news programs where people talk to each other, and try to extract things from those sources that may be of use to you. Before you have to use the language in a particular situation, like a phone call, try practising it before you do it.
