I used to model, and the agency I worked for gave us all classes on how to apply our own makeup for a job. They discouraged the use of eyelash curlers because over time they weaken and can even break off the lash, causing your lash to be shorter. If however you do decide to use an eyelash curler, I would recommend that you apply your mascara and use the curler before the mascara dries. BE GENTLE, and don't press too hard. You may want to heat the curler a bit first with a hair drier to maximize the curling power, just don't get it too hot. Also, begin by curling gently about 1/4 distance away from your lashline near the eyelid, then curl again about 3/4 of the distance from your eyelid. Still I really don't recommend using the curler. What I do instead is hold the mascara wand on the underside of my upper lashes for a few extra seconds, pulling them up by slightly lowering my eyelid but without moving the mascara brush. As I work my way toward the end of my lashes, I continually lower my lid. This doesn't create a curl exactly, it just causes the lashes to point upward a little bit and makes the eye appear more open.

As for adding volume, this is much, much easier. Whether you're using the small brush or the larger brush, place it on the underside of your upper lashes as close to the eyelid as you can get. Then slowly wiggle the brush back and forth (left to right) as you move the mascara wand toward the ends of your lashes. Let the first coat dry completely, then repeat with the second coat. Do the same with the bottom lashes, just applying the mascara to the upperside of the lash.

Hope this helps!