Okay, this is not meant as an exhaustive essay on how to make it as an actor. But these are some very practical words of wisdom...

There're a couple of basic rules you should follow in putting together your resume. First, you need to put certain information on it:

Your name

Your address and phone number, which includes your service and/or voicemail (if you have either).

Your height and weight along with hair and eye color (don't include your full set of measurements, but have them handy).

Your experience as an actor. Don't worry if you haven't got much. Keep in mind, though, anytime you understudied and went on for even a fraction of a performance in front of an audience, then you take the credit.

Your education, which includes major workshops and/or teachers.

Your special skills, the little things that often make a difference between getting the job and not (after all, Zorro needs to ride a horse...and you can't be on Baywatch if you can't swim). By all means include accents, but don't list them ("Puerto Rican? Too bad--we need someone with a Cuban accent!")

A few words of warning: Never, never lie. It is way too easy to get caught, and then no one has any reason to believe anything you say. Likewise never give your age, and let them figure out your age range from the headshot. Which brings us to...

Let's take a look at two of my headshots.

Okay there are good points and bad points with each. The biggest positive point about the photo on the right (was I ever that young?) is that it has my name on it. But it has several other problems. One is the shirt. In general solid colors, especially very light or dark ones, aren't as interesting as patterns or texture. Likewise look at my eyes. The older image seems to glance behind your shoulder, while the more recent one meets the viewer's gaze. No less important is the attitude shown. When younger, my picture frankly makes me look like a smartass (okay I was one, but that's another story...). The later photo is a friendlier, warmer image. Yet it is still interesting, as if I've a fun secret to share. One last point...the later picture was taken after I'd gotten a little bit of a tan. Notice how washed-out the older Me looks?

No actor is ever more vulnerable than at tryouts. This is one of those fundamental truths a surprising number of directors don't realise. So the best piece of advice I can give is "don't be terrified of hearing the word No." Accept that most auditions don't result in jobs, and that is fine. Every tryout is a chance to do exactly that--try out your audition skills. In other words, the unsuccessful auditions are rehearsals for the successful ones!
Keep in mind also that the single greatest trait a director uses in casting is memory. Leave a strong, positive memory and you will get work. That means don't do anything offputting or rude, or too weird, or disturbing. But even more important is to grab their attention in a good way. For this, don't be afraid. Cold readings, in particular, tend to make actors timid as they try (hopelessly, when you think about it) to give finished, smooth performances with all the right choices for the script. Although you should listen to directions (as a director myself, I can't tell you how often actors at auditions simply have not listened to what I told them), when it comes to making choices, a glorious failure is just fine. Go for drama. Go for tension and theatricality and humor and passion. Sear your performance into their brains! Remember, auditions are NOT finished performances where you interpret a writer's work with honesty and precision. No, auditions are sales pitches... and the sale item is you!