I've taken up learning German, again.
I've been learning German on and off for twenty five years, having done it for one year at school and then as an introductory course in my second year of university, and then having taken up various textbooks and readers over the years. Part of the motivation has come from wanting to follow up the family history, so I can read the letters of my grandparents and other documents. Wolfgang Harich's Autobiographisches Framgent contains information about the resistance group my grandfather and biological grandfather ran in Berlin during World War II, for example, while my great-grandfather wrote a little book Der bunte Alltag of "stories of everyday life" (published in Vienna in 1943).
This time I'm meeting with a tutor weekly, for an hour or so of conversation, in theory around a newspaper article I've read but in practice digressing quite rapidly. So a story about an insect-eating festival in Oxford led me to an attempt to explain the ecology and sociobiology of leafcutter ants, die Blattschneiderameise. Apart from improving my aural/oral skills, usually the slowest part of my language acquisition (having notionally divided the world's languages with my sister when we were children, and ended up with the dead ones), this also provides a regular prod to keep me going.
For grammar, I'm currently using Intermediate German: A Grammar and Workbook, a fairly simple text. When I get through that I plan to move on to Russon's Complete German Course, which is an old A-level textbook and is more in the old-fashioned "solid grounding in grammar" line.
I'm steadily reading through the three volumes of Penguin Parallel Text German Short Stories. A long-term goal here is to be able to read the second and third volumes of Peter Weiss' The Aesthetics of Resistance, which have not yet been translated into English, but I suspect that's not the easiest of texts.
I have only a little dictionary, and should probably get a better one at some point, but am mostly using dict.leo.org because it's much faster to look up words in a web browser than in a printed book.
For background on German I have read German: A Linguistic Introduction and parts of several similar books.
Something I haven't tried yet is watching German films without the subtitles, or perhaps German news streamed online.