You want to become an actor or model. Great! Being motivated is the first step. And you've sent in professional photos. But you haven't made a name for yourself yet, and so you get invited to a casting, along with tens of others.
Below you will find an overview on how exactly a casting works and how you can navigate it. You both need each other, thus a good synergy is important.
how does it work
You've sent in your portfolio to the casting agency. You'll get a reply shortly, hopefully with an invitation to come introduce yourself.
During your introduction you'll often have a photo shoot in different styles, with clothing you bring yourself. It is important to think about which styles you wish to profile yourself with.
The agency will suggest you to their different clients. Some will do this only when an assignment comes along that fits your profile, others will suggest you for a wider array of roles.
You get a call or email from the agency. Ideally, the shooting dates, location, budget and specific requirements (such as bringing your own clothing) are clearly described. You will often be asked to hold a certain date in option, because the client may not have decided when to shoot or with what team. Keep those dates free, even if you are not certain you got the job. Should you get another offer for those blocked dates, let the new client know that you have a previous option and that they are the second in line. You should never book two jobs on the same date, hoping you'll get chosen for only one.
There might be another casting round with other candidates. Castings are unpaid, usually take 30 minutes at most, and don't always take place at the casting agency itself. Sometimes, an external party will be brought in at a different location. You'll be given a place and time, and you'll usually get a script beforehand. During the casting you'll act out scenes from the script. Prepare well, learn the script and follow the guidelines. If you are unable to come to the casting, it is unlikely you will be considered during the selection process for the role.
potential call-back and fitting
When, in a commercial for example, a family needs to be assembled, side characters can be changed in function of the main character. If the commercial revolves around a child, parents will be cast accordingly. That's why you may have a first casting to determine whether you can take on the role, and get a call-back a few days later for a second casting with actors playing opposite you. That call-back date initially won't be mentioned on the casting invite. If you do get chosen, a fitting may also be organized, usually the day before the shoot. You will have to try on different clothing. This fitting date will also not usually be mentioned on the casting invite.
During the casting, ask when the decision is set to be made. Sometimes, this will be the day after, sometimes it can take more than a week. During this entire time, you will have to keep the shooting dates blocked on your calendar. Most casting agencies have the decency to let you know whether or not you have been chosen, but some you will have to contact yourself for an update. However, silence usually means you did not get the role. If you receive another offer for the same shooting dates before the decision has been made, it doesn't hurt to contact your agency about whether or not they have news yet.
on the job
If changes are made to the script, not previously discussed things are asked of you, or if things don't go as planned or expected, contact your agency immediately. They are your first point of contact in case of any problems.
after the job
A casting agency likes to get a short report on how your day went. Overtime or extra costs can be discussed, and behind the scene photos are often appreciated. This email will also strengthen your bond with your agency and shows your gratitude.