Put mirror brackets in areas where they won’t interfere with the cutouts. Some mirrors have cutouts quite close to the edge, and putting a bracket right next to one may cut into the circle and make it look too visually busy. Put the brackets alongside portions of the mirror that aren't right next to the edge of a cutout. Arrange the brackets so that they are as evenly spaced as possible, although this may be a little tricky when taking the cutouts into consideration.
Use spreadable adhesive only instead of adhesive pads, if you choose this method. If you make a mistake when applying the adhesive pads to the back of the mirror and crush one of the pad's corners or create a ridge, the mirror won't sit evenly on the wall. The unevenness of the gap between the wall and mirror will be visible when you look at the edges of the cutouts
Position the mirror carefully if you use adhesive. If you push the mirror around on the wall, extra adhesive can stick to the wall and show through one of the cutouts if one ends up over some of the smeared adhesive. This creates extra cleaning work for you and does not look very neat.
Avoid hanging the mirror by hooking the cutouts on nails or wall hooks, even temporarily. The hardware can chip the edges of the cutouts.