Leave early in the morning, pack enough water. The last part is rope insured. Overall, alpine experience is useful. You should be sure-footed and free from giddiness.
The gondola takes you comfortably from the Seegrube up to the Hafelekar mountain station. From here you have a wonderful view of the Karwendel and the Inn Valley. Information on prices and travel times can be found here: nordkette.com.