Gerbera daisy petals bruise easily. Bruised petals turn brown and shrivel a bit. Those brown petals look unsightly in an arrangement. Handle the flowers by picking them up by the stem just underneath the flower.
The stems are hollow and not as strong as others. The advantage is the flowers will arch in an arrangement. The disadvantage is the stems can break as they are being poked into the floral foam of the arrangement. Use a wood skewer to poke the hole in first, then insert the daisy stem into the foam.
The flowers are big, but they also are heavy. Those heavy blossoms put a strain on the stems. The flowers won't usually snap off the stems, but they will bend it to the point the blossom is floppy. When that happens, the stem can't get water up to the blossom, causing it to wilt.