German can sound a little harsh and aggressive when you first hear it. When Germans speak English they are often perceived as being rude or perhaps a little blunt. Why is this? Well, German is a very direct language and when directly translated into English it gains a rude or blunt edge that isn't there in the original German - so don't get offended, nine times out of ten you're not being insulted!!
German is a very grammatical language. There seem to be grammatical rules for everything and for most people it can be a bit of an uphill struggle trying to learn it. The majority of us will find learning German difficult, but if you stick at it you'll eventually be able to speak a very expressive language and be able to make lots of friends in Heidelberg. It is always appreciated when you at least try and speak German to the local people.
What's the best and quickest way to learn German? That depends on you. There are lots of different ways... buy yourself a German book.... attend evening school.... live in Germany.... and so on. We can't really help you much here. You're going to have to try out a few of the different options and see which one feels right for you.
If you live in Heidelberg read on.....
... and would like to learn German there are a number of options. The cheapest is the Volkshochschule which provides German lessons (at different levels) for foreigners at very reasonable prices. The draw back is that the classes are often pretty large, sometimes more than 20 people and the pace can be frustratingly slow. But then again in this life you get what you pay for.
If you have more money to spend, then have a look for the language school adverts that appear in the Rhein-Neckar Zeitung, the local newspaper. Expect to pay 30 DM + an hour.
Berlitz have a language school in Heidelberg. You will pay a premium to learn German there, but the quality of the teaching is generally high and the classes are small.