An easy-medium hike for summer, and a classical winter hike with great views of Mittenwald and Wettersteinspitze, however in winter one needs to use crampons (and possibly ice axe).
Reaching the start point: The start point of the route is MIttenwald HBF, which can be easily reached by regional trains from Munich. The cheapest ticket would be Werdenfels ticket.
Ascent: From the train station turn left, and after crossing the village we reach Karwendelbahn. This is where the hike starts. The route up to Mittenwalder huette is mostly easy and is basically a zig zag path. Some small sections are secured by cables.
From the hut, walk towards right. After 100m or so, the path bifurcates. The left route goes to Karwendelspitze, while the right one goes to Lindenkopf. The route is along a narrow, sometimes exposed path. Again tricky sections are secured by cable, but the cable itself might be covered in snow in winter, so one must bring appropriate equipments in winter (crampons, ice axe). Just before the final ascent, we need to tackle a steep slope, after which it's just a gentle walk to the peak.
Descent: Follow the same route as ascent from the peak to the halfway to Mittenwalder huette. There is path towards left going down. Follow this zigzag path all the way until it merges to the original path.
Note: In winter, it is recommended to use the same route for descent as the one used for ascent, because the descent route is not used frequently and could be tricky.