The first step in stalking a predator is to learn everything about the animal you can using the various resources available to you including people, books, movies, and the internet.
The second step is to spend some time in their habitat. The more time you spend there the better you are able to apply the knowledge you just learned.
A couple good method's for putting a stalk on any animal is to find high ground for easy observation. Grab some optics and watch cutouts in the timber and natural routes a Lynx might use. If the Black Forest does not provide observation posts, then you can follow signs (tracks, poop, fresh kills).
Learn to identify a Lynx sign versus all the other critters in the Black Forest woods. Once you can do that, learn to age the sign. Once you have a 2-4 hour old sign, follow it. There is plenty of information on tracking animals available but the idea is to look for tracks with fresh poop, fresh kills, or minor weathering, those tend to be the freshest.
If that is not interesting you could try and call them in using various predator calls. You could use trained dogs to trail them. By pure chance, you could cross paths with one.
The most valuable resource is people in the area with first hand knowledge. If you can get someone to help you through the learning curve I have no doubt you could spot a Lynx on your first few tries. Stay optimistic, most animals prefer to avoid humans, so a little care while wondering goes a long way. Either way it sounds very exciting and worthwhile, be safe and good luck.