Trying to Learn a language

Hey everyone,

I'm trying to learn German again. I've wanted to learn for years but have always had really bad memory problems. Hence trying to learn it at school didn't go too well, rote learning is tricky, just couldn't retain it, I know that was like a gazillion years ago, but I'm having another go.  But puzzling over how the heck to get it to stick in my head?

Any tips?

I store hundreds of number plates in my head of all the cars in the neighbourhood in a wide radius (but only on sight if that makes sense) if you ask me to recite such-and-such's licence plate I haven't got a clue, I have a massive database of groceries & their prices in my head (nightmare when it all keeps going up week on week!) but this language thing just keeps confounding me!

It seems like some information is just sucked in by default, I mean not by choice, where some information you actually want to retain, is like trying to shin up a greased pole???