I'd recommend a trip to an English speaking country in first place, BUT you have to make sure, that the place you are going to is not crowded with Germans. Otherwise you will end up spending all your leisure time with them in spite of the 'locals' and won't have considerable improvement (because you WILL switch to talk German, believe me). Once you dream in English (and it happens and no it won't take years) everything goes much easier.

And well for the technical terms see the answers above. ER, etc....
I'd just add some writing or a hospital internship to the point of watching the movies all the time. Because understanding words is one thing, using them a different.