If you have a degree you probably will not need to list all your O Levels/GCSEs;
just listing the number is probably sufficient.

Professional Qualifications
List your professional qualifications, certifications and membership of
professional associations.
If you recently completed a college or university degree or HND or
Diploma, etc, then you may want to list the courses you studied if the subject
you studied was relevant to your target job.

Training Courses
List any work related training courses which you attended, including
company courses and any you attended on your own initiative. If you obtained a
qualification on any course please list it. You only need to list the important
courses you attended; no one really cares if you went on a time management
course as everyone gets sent on these courses!

Work Experience
If you have been working for a number of years you probably do not need to
include any part-time jobs, vacation jobs, voluntary work or unpaid work
experience. Charity work could be included in your interests. However you might
want to include these jobs if they covered a period of unemployment, or a time
when you were not working for any other reason, or you feel that some of the
experience you gained will be useful in your next job. You should normally
concentrate on your two most recent jobs (unless you were only there for a short
time), because employers are usually most interested in these.
Start with your most recent or last job and work backwards. For each
position (treat internal promotion as a new job and record the dates separately)
list your job title (e.g. Manager, Supervisor, etc), the job title of the person
you reported to (e.g. Director, Manager, etc) and when you started and finished
in each job. Give the name of the company and include a brief description of the
service they provide (using the terms they would use to describe themselves).
Set out your main responsibilities, achievements, duties, and skills that could
be transferred to another employer. Be specific and positive about your skills,
e.g. 'good written skills' may be a better description of your abilities rather
than 'good communication skills'.
Include your level of responsibility if any, e.g. 'responsibility for
departmental budget of £100K and managed 10 staff'. In particular list any
achievements you had in each position, including increases in sales/productivity
and cost savings made. Quantify your achievements if possible. 'Increased sales
by £100K' is more interesting and positive than just saying 'Increased sales'.
You should try to include some achievements such as meeting deadlines, budgets,
etc, and any information that may be relevant to your next job.

Major Achievements
When you are listing your achievements in this section, only list 3 to 6
of your most important work achievements; your other achievements can be
described under the work experience section. You should only list achievements
which are relevant to your next job and indicate how you achieved them.
This section is very important as an employer will only invite you for an
interview if they can see a benefit in doing so. Your achievements may sell you
to an employer and make them choose you for an interview rather than someone
else. For this reason it is vital that you think carefully about your
achievements.

Other Experience
List any relevant skills you have, especially any transferable skills from
previous jobs.
If you have foreign language skills which may be relevant for any jobs
which you are applying for, please list them and indicate whether your skills
are spoken, written, business or technical. Please also indicate your level of
fluency: fluent, good working knowledge, etc. You should only list these skills
if they are relevant to the jobs you are applying for as no one really wants to
hear about a French language course you did at school a long time ago.

Interests / Hobbies
List your interests, hobbies and any sports you play. List any positions
of responsibility you hold or have held in any club or organisation, and say
what your responsibilities and achievements were.

References
You do not normally need to list referees on a CV, but it is a good idea
to think about whom you could ask now. For some professions however it is normal
to list referees; these include the teaching and health service (NHS)
professions - your referees in these professions are often asked to provide you
with a reference before you are even asked to an interview.

Summary
List your major skills, strengths, personal qualities and achievements. Be
specific, e.g. good team player, excellent written skills, versatile, able to
motivate others, etc. Look at your staff appraisals or at your references.