How to develop a good theatre/performance CV

A good performance CV is extremely important for any actor wanting to get work with any company.
For applying for a job involving Shakespeare, for example, your head shot may not even be looked at if you don't have at least one Shakespeare Credit in your CV. Even if it was a profit share performance or even an amateur production from before you went to drama school, it would still help having an example on your acting CV of what you are applying for.
On casting websites with an online CV, such as Spotlight or CCP, it's fairly easy to put down every production you've ever been in as the page can be scrolled down and they are usually quite easy to read.
I would recommend though that after you have been working professionally for long enough and have gathered enough credits, not to have every drama school play credit on there in case employers will think that most of your experience was during your training. By all means leave some there, especially if it's an example you don't have professionally, but don't clutter it up with every scene study, 1st and 2nd year show and the much under-mired credit showing 'Various Roles' as your character as it may make you seem a little too eager to show off your 'diverse' range.

Many companies, to test the commitment of an actor or to simply not look at hundreds of online CVs, will ask you to post a head shot, covering letter and paper CV for consideration.

A paper CV should be a lot simpler than an online CV and the credit list should be a lot shorter.
It should have a small head shot in the corner,possibly one similar but different to the 8x10 also in the envelope and have your performance name, height, age range, build, hair and eye colour and contact phone and email address all at the top in an easy to read font and size.

Now for the credits, I recommend putting no more than ten credits on the CV. Even if you have fifty that you're extremely proud of, the reason being that putting more than ten and not only will it look like you are showing off, but also you will either have an overly full and cramped CV with tiny text or bad spacing or it will go on to two pages when one really is enough and you'll be saving paper.
Also with ten it is easy to show off your varying experience. You can easily have one serious play, one comedy, one tour, one panto, one advert, one short film, one musical, one classical play, one TV credit/film credit or a mix and match of varying characters you've played in any of these.
Also in this format you can swap and change credits easily depending on what your applying for. Say you're applying for a comical role, be sure that out of your ten credits that it's comedy heavy. it may be just a case of changing two or even one and then printing it out and sending it off.

I'd recommend separating Filmed and Theatre roles as then it's easier to read and easier to see that you are experienced in both (if you are) and to put the title of the show, the character, the director for both but for Theatre credits put the venue of the performance and for film credits put the production company.

Also like the online CV it's a good idea to list accents you can do and skills outside if acting you have in case they come in handy. Even if it's something as small as sketching (if you are skilled at it) it's something that may come in handy during the performance or production side of the project you're applying for.

I'd say try and use a pinch of colour and shading on your paper CV for though it is a bit more draining on ink, it will help yours in particular stand out if it has elements of blue, or a striking border.
There's no need to put secondary school grades or a reference on the CV as the ability to do AS level maths or a good word from a previous employee doesn't usually mean that you will be suited for a completely different production. And if the employer is good enough they can usually tell if you will be easy to work with from the audition.

Lastly and simply, may be obvious to some, but sometimes it's not to others, don't hand in a performance CV to a job that is not for a performance! For example for ushering work in a Theatre or a temping job. Use a 'normal' business CV for them as an employer of waiters and barman will only see an actor looking for temporary employment and will often go for someone who is looking for something a lot more long term than from someone who is just looking for a job until the next acting job comes along.