The following DOS and DON'TS were offered to me anonymously by agents and casting directors who are, frankly, baffled as to why common sense just doesn't prevail with some actors.

1. DO let your agents know as soon as you can when you're booking out.

If your agent calls with an audition, it's okay to ask when the callback and shoot dates are because you might be unavailable on those dates. If you wait to ask until after the audition or after you've booked the job, you will not endear yourself to your agent. You will also infuriate the casting director, who will look bad in front of his or her clients, who spent hours choosing between you and another actor, only to find out that you aren't even available on the shoot dates.

2. DON'T change your look between the callback and the shoot.

Is this painfully obvious? Not to everyone. Last year, an agent I know almost went crazy when a client booked for a commercial cut his hair right before the shoot-and the spot was called "Bed Head." When he got to the set, the director discovered that the actor no longer had enough hair to look appropriately tousled. Production shut down and furious meetings ensued while they debated whether to replace the actor or add hair extensions. Luckily for the actor, they opted for the more expensive option of adding hair extensions, which also added hours to the day's budget.

3. DO update your pictures as your appearance changes.

I'm close friends with a commercial CD who regularly pulls out clumps of her hair when she thinks she's bringing in a 7-year-old, based on the child's headshot, only to find that she's bringing in a 10-year-old who is a foot taller than the out-of-date picture and résumé indicate. Uploading a new photo and résumé is so easy to do, right from the comfort of your home computer.

For adults, this means letting your agents know as soon as you change your hairstyle or gain 20 pounds or decide to let the gray in your hair shine through. But if you arrive at an audition looking quite different from your picture, you'll have an unhappy CD, who will readily call your agent to express his or her displeasure.

Online résumés need to be updated too. For some reason, many actors seem to think this is part of the agent's job description. It isn't. Also, keep your online résumé current with new skills (like improv) that you may have acquired. Telling your agents isn't enough; they won't remember.

You might also consider adding your mobile phone number to your online résumé, though I know not all agents agree with this. I once booked a great print job as a last-minute replacement because the casting director found my cell number on my résumé on a Saturday. I was on the set 30 minutes later shooting the spot.

4. DON'T request a time change unless you really have a conflict.

It's inevitable. You get an audition for 5 p.m. on a Friday, when traffic is at its gnarliest. CDs know this is not a favorite time slot, but someone has to be seen then. Agents and CDs will notice if you're an actor who continually asks for a time change. Try to keep this to a minimum, saving it for when you really have a conflict and not when the appointment is merely inconvenient.

Sometimes an actor will be a no-show, figuring that no one will care or notice. People do notice, and it reflects badly on you by robbing the CD of the chance to fill your slot with another actor. Moreover, by not showing up, you limit your agent's ability to earn a booking by suggesting another actor to the CD.

5. DON'T say yes to a show on the spot.

Have them call your agent with the offer. Agents are a buffer between you and the ugly world out there. Sometimes they can get you more money or better billing or a parking space. Sometimes they can't. But as you're paying them anyway, you might as well let them do their job.

Written By: Paul Haber via Backstage