Step 1. Fasten the suspenders to the back of your trousers. Don't attach the clip over the belt loop. Try to attach them to waistband material itself.
Step 2. Raise the suspenders over your back and lift the suspender straps over your shoulders. This will usually position it just over or outside your nipple.
Step 3. Let the suspenders hang and clip them where they naturally fall on your trousers.
Step 4. Slide the buckle to shorten or lengthen the straps to get the perfect fit. The suspenders should look even and feel comfortable.