Sktchy app is such a great resource for finding people to draw. Here are a couple of gals drawn/painted in Procreate on the iPad.
I took a class on Schoolism.com with Jason Seiler about drawing realistic portraits that was very helpful. This was part of the homework for the class, drawing lots of eyes. Above is one from Sktchy app and below are from photos from that class, the web and people I know. The next one below is my son Robin. All are done on the iPad in Procreate.