You need to organise the following essential items before you even get your first interview, let alone an agent and/or your first job. You should start planning for all these in good time before the end of your training - ready for your first public production:
1) Join Equity! You can join (very cheaply) as a student member (see www.equity.org.uk/HowToJoin & click on Student Membership) and for a small extra fee reserve your professional name - details of how to go about this are on the website.
2) A good, strong professional name. If you can't (or don't want to) use your real name, it's important to select an alternative that you're completely comfortable with.
3) Well-designed headed paper. Beatrice Warde, the passionate typography expert said, "Typefaces are the clothes words wear." Find a typeface that 'dresses' your professional name well.
4) Secure and reliable telephone & internet connections for professional use. Note It is very important that your outgoing message & e-mail address sound professional and not like hangovers from your adolescence.
5) A reliable computer with printer. Tip Laser printers provide a much crisper quality when printing text - and laser toner is much cheaper, per page, than ink.
6) Up to date copies of Contacts and Actors' Yearbook.
7) A good set of photographs and sufficient copies.
8) A well laid out & up-to-date CV. Notes It's important to ensure that all spellings of proper names (directors, play titles, etc.) are correct. It's also important to understand how to convert your CV into Portable Document Format (PDF) for e-mail transmission.
9) A good standard letter which you can adapt for individual circumstances & use in e-mails, etc.
10) A dozen (or more) varied audition speeches. [See my Alternative Shakespeare Auditions (for Women & for Men) & MORE Alternative Shakespeare Auditions (for Women & for Men) for help in this particularly tricky aspect of auditioning.]
11) Half-a-dozen (or more) varied audition songs.
12) A mental list of things (not just acting ones) you could talk about in order to respond to the almost inevitable, "What have you been doing recently?"/"Tell me a bit about yourself?"
13) An entry in Spotlight - details at www.spotlight.com/join. Note Entry into Spotlight is strictly limited to professionally trained and/or professionally experienced performers, and applications are always vetted.
14) A reasonable selection of clothes for interviews & auditions. Essentially, you need to feel comfortable and appropriately dressed for each individual circumstance - and you will face a wide variety of such circumstances.
15) A budget. The costs of the above can accumulate quite quickly - before you've earned a penny. And there are many other minor things not listed: postage, Equity entry fee and annual subscription, subscriptions to The Stage and other professional publications, travel costs to interviews, and so on. All the above items can easily add up to much more money than you might think - you need to calculate your potential professional expenses and budget for them. Note Although many of the above are allowable against tax, don't forget to include your potential tax bill! Another note At the outset of your career, consider carefully the cost-effectiveness of items like personal websites, showreels, etc.
16) Sources of non-acting income that are that are flexible enough for you to drop at 24 hours' notice - at an educated guess only about 10% of the profession earn a living solely from acting. And, even for those, incomes can be incredibly variable - £200 one year to over £20,000 the next to quote just one example.
17) A working knowledge of the nation's transport systems (especially London's) - you will often not know where you might be required for audition/interview (even work) until very late in the day. Tip As a general rule it is wise to double your estimated travelling time to allow for the almost inevitable foul-ups.
18) A great deal of patience, persistence, determination, cunning and resourcefulness.
19) A stoical source of solace for the bad times. Tip Find another activity which absorbs you as much as acting does.
20) A copy of my An Actor's Guide to Getting Work for reading on the loo (published by A. & C. BLACK).

GENERAL:
Can you organise yourself? Acting can be an instant business. For days/weeks/months/years nothing happens and then a few minutes/hours/days/weeks/months/years later it can all be happening. You must always be ready but not constantly on tenterhooks. In spite of the popular image of the chaotic, dizzy actor, you have to be personally organised or you could significantly harm your employment prospects.
As an actor you are your own business. You are not only your own work-force but also your publicity and public relations office, accountancy division, typing pool, transport manager, and - above all - managing director. Of course, you may well have an agent, an accountant, a friendly typist etc., but none of these people can do anything unless you give them clear direction. You are finally responsible for your success or failure in the business.

Simon Dunmore
Updated, September 2009

Please e-mail me, if you have any comments.