I am working on my second novel now, the first one is here: http://lamatpress.com/titles/itm
While these two of mine are traditional novels, you probably want to self-publish a short novel on eReader these days. Focus on something in the 20k to 40k word range. Make it full of romance, intrigue, suspense, and some humor. Sell it for $0.99. Cash follows.
If you want to go print, consider places like CreateSpace or Lulu, that take your Word file and print a book out of it to your specs. I use them to get the drafts and review copies printed, and it's incredibly motivating to have your own book in your hands well before it is available in print.
Don't go traditional publishing. Not because it doesn't pay well, but because it takes forever. It will probably take you over a year to land an agent. Then the agent will negotiate for another 1.5 years. After that, it takes the publisher another 1-2 years to get their act together. And by the time your novel comes out, you are already a grandpa. ;-)
EDIT: Ok, I realize now you are a Berliner. The German market is potentially totally different, in particular I do not know the penetration of eReaders and the availability of CreateSpace/Lulu there.
But, hey, at least I know you are a delicious cream-filled doughnut!!! :p