How best to apply minoxidil when I have thin hair all around my scalp, not just one spot

My hair has been thinning all around my scalp for the past few years due to my medication, and it's not an option to change it(daily chemotherapy med for CML). Hair loss is usually not a side effect, but I'm one of the lucky few who experience it.

Background out of the way, what's the best way to apply minoxidil to my whole scalp? I was thinking of combing over and applying/massaging every couple of inches or so, but I believe that would be too much.

Any suggestions?