@karstengweinert hi and thanks for asking. do you practice as well? :)
so, i alternate "metta" and "breathing" days. "breathing" days are just 18 minutes of breath awareness.
on a "metta" day i will do 6 mins of breathing - 6 mins of metta - 6 mins of breathing.
in the 6 mins of metta, i start with the easiest person to love. i adapted the metta aspirations to "may X be happy, may X be healthy, may X be safe". that felt right for me and i felt free to adapt since everybody seems to do it with slightly different words. i mentally repeat them while breathing into the warm "lovingkindness feeling" in my chest. but generally being open to all emotions that might arise. right now, i only do the first two steps (benefactor and myself), because i am just starting.