Yes, casting managers and agents do read it. A bit. Your aim is to provide useful for them (and for you) information in the most short time possible; the problem is you cannot know exactly what will it be. But at least you can do other important things that will certainly help you look more professional.
Cut, cut, cut. The more you put in your cv, more difficult it is to read. Leave to the reader only the information that may be really useful. Here are 3 things that shouldn’t be in your resume, if you audition as an opera soloist:
Chorus work. Very common mistake - but the jury isn’t interested in your career as a choir singer in this case. Cut
Scenes, duets&trios performances. Only shows to the jury that you didn’t have enough experience to write about, so you’ve decided to insert in your resume even your acting class exam, and frankly they are not very interested in this information; or, worse, the reader will not pay attention and will decide you did the whole role, and that may create a big misunderstanding that should be avoided. Be professional. Cut
Recitals with piano. Writing one or two recital performances in your resume will only do worse; if you have a lot of them, they will occupy too much space. Cut
Exceptions: very important performances in all three cases. Sang in the choir of Teatro alla Scala or in Metropolitan Theater? Write this. Performed an excerpt of the opera during BBC Proms, or worked with Ricardo Muti? Go for it. Did a solo recital in Philharmonie Berlin? Mention it. But find the right way to write these things: for example, “recitals in prestigious concert halls, with Philharmonie Berlin among others”. Clear and clean. And, by the way, don’t overuse the “among others” thing - balance, remember?
Structure&define. Simple as it is: use the italic for titles, at least. You may also consider underlining the most important things - but be sure they are really worth that. If you write your resume with the timeline, put your most recent engagements first; or, if you really feel like it, sort them on the scale of importance - but be sure you perceive this importance rightfully. And, obviously, check the grammar thoroughly.
At one point you will need to understand what is the good experience to mention and what is not, and how to provide the information about it. If you are auditioning for an important theater, putting the role of “La cena è pronta” that you sang in your College production is definitely not a good idea. One day some masterclasses you’ve paid for unfortunately won’t have place in your resume anymore, because you will need to mention more important experiences. It is a normal pace of your growth, so be sure your cv is updated according to your career path.
Good resume is very important for your success. If people see that other professionals have already trusted you, they are more keen to give the opportunities to you. So make a treasure of what you have in your cv, and you will have more possibilities to enhance it in the future!