As a matter of practical experience, learning a language is about hearing it used. That's how all children learn.
The best german starter lessons I heard of, was a german women in Ingolstadt, who was teaching brits beginning with infant school books, instead of jumping them straight into more advanced grammar, like VHS, Berlitz and co. do.
I learned German by going to the cinema and watching films I had already seen in english (you know the plot), watching lots of news on TV (generally good diction, short sound bytes, etc). 20 years ago adverts were also a good source to learn basics, but they've degenerated to "denglish" -- A handy is very handy, but it is still a cell phone;-)
Back this up with reading newspapers, pamphlets, illustrated magazines.
Submersion is important. If you hang out most of the time in an english speaking environment (Irish pub??) it makes learning german difficult, as you always have the easy option.
Okay, so I never got round to taking "proper" lessons, although I did have a go at working through a book recommended by a friend of my mum's, who is a german teacher in GB. Gave up when I figured out that I did grammar by "feel", and the germans are generally just as bad at german grammar as I am at english;-) Still, it gives the kids something to laugh at
The main thing is to get a feel for the language which, as said, first comes by hearing, then reading, then speaking comes along on it's own. And don't be shy about saying things wrong... When "foreigners" do it in english, we know what they meant, even though we did hear what they said. Vice versa is ditto.
My achiles tendon is articles. It is important to learn the appropriate article with the word -- something I didn't, which increases the amusement of my kids, along with declination.
The hardest part in public is that so many can speak some english, they nearly always try to be "helpful" when you get into difficulty in german, and start speaking to you in english.
Übung macht den Meister