Your role as a devil can be formally ascertained from the Bar Council but a potted version could summarise it as follows -
Reading and thinking about advocacy and life at the bar is an essential form of self-education. The best all-round general text on advocacy is Keith Evans, Advocacy in Court (2nd ed.) (London, 1995). Many other works are also available on this subject.
Learning actively involves taking the opportunity to read papers before your master goes to court (and asking for the opportunity to do so); asking any question on your mind, however "stupid" (because your master is there to answer the stupid questions, and asked them to his or her master before you); reflecting on the experience after any court outing; and generally keeping your eyes and ears open and your mind active in relation to what is happening.
Your attitide is an important factor here. Some lawyers contend that "[t]here are many cases you cannot win; there is no case you cannot lose" (C. Michael Abbott, in Ron Liebman, Shark Tales (New York, 2000), p. 95). Which makes it important to think positively about your cases and your master's cases. If you flinch under fire you will handicap yourself seriously.
Learning actively also involves attending all compulsory CPD courses and any voluntary CPD courses that you feel would be of assistance. It may also be useful to ask yourself what have you learned as you go along, on a regular basis.
Availability means being contactable, which tends to involve possessing a mobile phone and answering it where possible, having access to a computer and email, and regularly checking your emails. It means acknowleding texts and emails promptly. Useful techniques include putting the title of the case in the subject line of the email so that the email can be found later.
Being contactable also tends to involve showing up on time and preferably ahead of time in the Library prior to cases/consultations.
It means being reasonably organised and carrying a few essentials at all times - your diary, a pen, a highlighter, post-it (R) notes, a large notebook preferably in the form of a yellow legal pad. You should then use these appropriately, and get into the habit of making a note of court hearings, consultations, etc. Learn how to take a proper note and to include basics such as case, date, dramatis personae etc. Bring the Rules of Court with you as a matter of routine.
You will need to learn rapidly where all of the courts are and how to find the court you need to be in. An excellent exercise is to walk around all of the courts in the Four Courts complex yourself and locate where each is.
Being a devil means you will do a certain amount of minor court appearances for your master. When doing so you must immediately update your master on the outcome of any such appearance that you have been asked to undertake on his or her behalf. You will also accompany your master to consultations and court appearances.
In addition you will do a certain amount of drafting (for this purpose access to a computer and appropriate word processing software is usually required). Your master should be able to supply you with useful precedents so ask for an appropriate precedent or failing that consult Bullen & Leake & Jacob's Precedents of Pleadings. When asked to draft, the major sin devils tend to make is "underpleading" - noting certain issues without going on to draft all necessary pleadings. To avoid underpleading you should draft full replies to correspondence, including cover letters - if only for your own practice, since your drafts will be radically changed before the actual reply is sent.
Unfortunately being a devil means doing the less salubrious tasks such as photocopying - however bear in mind that this is necessary to renew the cycle of life and that your master did the photocopying for his or her master when he or she was a devil. It is generally better to paperclip rather than staple photocopies as they may need to be copied again or bound in a book of authorities. Also make sure you have some kind of suitable bag or case to carry papers around in so that they don't become tatty and dog-eared, and that you will return papers to your master in the same condition as you received them.
Being of assistance also means having useful skills. An ability to drive and a full driving licence is normally a significant asset.
The rules for devils and the code of conduct for barristers are available from the Bar Council so obviously you must familiarise yourself with and comply with those rules and that code. In the event of any problems contact your master or the professional practices committee. As well as the mandatory rules of professional obligation you should also inform yourself of, and discuss with your master, issues of etiquette and tradition which may not have been incorporated in the written code of conduct. For example shaking hands with colleagues is often frowned on so you are better not initiating it. Another perhaps minor point - more rigorously enfored abroad than here - is that a togged out barrister does not usually carry a bag, although pushing trolleys or carrying papers in the hand is acceptable.
As regards court costume, the Court of Criminal Appeal has ruled in The People (DPP) v. Barnes, [2006] IE CCA 165, Unreported, CCA, 21st December 2006, that it is inconsistent with respect for the proposition that counsel may not be required to wear wigs for a judge to make arch (or any) remarks about whether they are so equipped or not. Taking that as read, the pros and cons should be debated with your master so that your individual choice in the matter is an informed one.
Equip yourself with all appropriate costume and other accoutrements well in advance and know what to do with them. You won't be able to do any work if you don't have the essentials. If in doubt about what to get or where to get it or what to do with it ask your master in advance - he or she will also advise you about useful additional items such as a wig box or brief bag. Don't leave all this kind of thing to the first day of term or later!
To stay on the right side of the line at all times make sure you don't be reticent about admitting you don't know things. Don't appear to be claiming to know more than you do know. If in doubt ask (your master in the first instance); don't walk yourself into trouble.
As time goes by you can look for opportunities to develop your own career. These could include opportunities such as the following depending on your own interests: