The most important thing an actor should have is an arsenal of material to perform at the ready. You need a rehearsed and polished sample of every style of song or monologue (classical, contemporary, funny, and serious) ready to perform at all times.
Your 2nd most important tool is a fantastic headshot. It is your business card. If you are under the age of 16 you should not spend a lot on pictures because your appearance will change. You will probably need new shots taken every year. However, if you are an adult, this is where you are going to want to spend a little money. A really good headshot is very important. Your photo is the initial meeting you have with agents and casting directors so it needs to make a good and lasting impression on them. It must be the best representation of you and your personality.
You should find a photographer who specializes in headshots for actors. Look at their book. Do their shots jump out at you? Look at the eyes, are they saying something? If not, find another photographer. Once you have picked a photographer they should be able to tell you what to wear that will photograph the best. And for a woman, they should have a make up artist available for you (about $150 extra, but well worth it). Make sure you have a couple of different looks, commercial & musical theatre, (usually smiling), a serious shot for soaps, TV and film, and possibly a business shot (for adults).
Once you get the photographs done, the hard part is picking 2 or 3 of your favorite shots. You may want to get some different opinions from friends, family and anyone you know in the industry. You do want to look your best, but make sure you look like your picture so the people you are auditioning for are not surprised or shocked when you walk in the room.
When you have made your choice of shots, take them to a reputable reproduction shop. My recommendation is Reproductions in midtown Manhattan because they will know exactly what to do. You will have a few options to choose from but I recommend that you consider a composite shot so you have all your different looks on one 8×10. Make at least 100 copies of whatever you decide. You might want to invest in some postcards as well, but more on that later. You will also have the option of putting your resume directly on the back of the shots (which could be a problem if you want to add or change your resume) or you can just staple them on the back.
When writing your resume, it should be in a 3 column format. If you have access to the resume of a working actor, copy their format. Otherwise here are the instructions in a nutshell. Your name should be centered along with your contact info below it. You want to list your show categories in the first column, the role you played in the 2nd, and where it was done in the 3rd. You do the same for film and any television. At the bottom of the page list your training, vocal range, dialects you have perfected and any special skills. Be concise as possible. You do not want to bore them! Now you can call yourself a professional actor. All you have to do is get the job!Image Source: http://images.google.com
