Your CV has one objective and one objective alone - to secure you an interview. This document is a sales device that needs to visually and accurately reflect you as a person, your skills and your experience. Moreover, a well tailored CV will have been tweaked specifically for the role that you are applying to, in order to highlight why you are indeed the correct person for the job. Whilst everyone will have a general CV, just sending this document out will be akin to playing the lottery and hoping it strikes a chord with unknown employers.
The most successful applicants will tailor and tweak this document to each specific role that they apply for. The best way to do this is to keep a template CV and tweak it accordingly each time you apply for a role. You will have been involved in many pieces of work during your career and if you included all of this on a CV, you would not produce a concise appraisal of your work experience. Therefore it is important to consider which pieces of information are relevant to each and every role that you apply for. Whilst you are encouraged to put a positive slant on things (for example, do not be afraid to list any cost savings that you made previous employers) never lie or exaggerate (for example by vastly over-estimating any such savings) as generally you will be caught out. Furthermore, NEVER leave gaps in your CV, this is viewed as suspicious. If you were travelling, ill or just taking a sabbatical, include this in your CV timeline.
The First Impression
This is exceedingly important. If you do not catch the interviewer's eye within the first 30 seconds of them picking up your CV, the chances are that an interview will not be forthcoming. Put yourself in the position of the person sifting through a pile of CV's. The more CV's there are the harder you will have to work to become noticed. For these reasons, always start you're your personal details, a personal statement followed by your work experience (only start with your education if you have just left full time education.) The employer wants to be told within the first 30 seconds, why they should invite you to an interview. Specifically, for technical roles include a skills matrix that is easy on the eye and lists all the technologies that you have used succinctly and under broad categories.
Aesthetics
If a CV is disjointed and written in the font "courier", the chances of someone reviewing your CV for even 30 seconds is small, regardless of the content. A CV should be easy on the eye, nicely spaced, with key points that jump out at the reader. You want to make it as easy as possible for the decision maker to pick you for the interview. Your CV should be logically ordered into certain sections with subsequent headers and section breaks.
CV Length
It is a popular misconception that all CV's should be 2 pages long. This is incorrect. What a CV should do is reflect your skills and experience accurately in a manner that is as concise as possible. Candidates that have just left full time education will be looking at a CV of 1 - 2 pages in length, but someone with 20 years + experience will be broaching 4/5 pages. Going over 5 pages is a bit excessive and employers generally are interested in your more recent work experience, so experience from sometime ago can generally be put into a précis that briefly says what you did whilst offering the employer more information if they feel that it is needed. Overwritten CV's tend to waffle. Be concise and to the point throughout your CV. Underwritten CV's offer too little information for the employer to go on, which will result in a failed application. Balance is the key.
CV Organisation
Your CV needs to be well organised and each section should follow on logically from the next. In this way it helps the person reviewing your CV build up a mental image of you as an employee. If it is difficult to follow, you are putting obstacles in the way of the employer picking you. If they cannot find what they are looking for they will move on to the next CV.
Common Mistakes
The most common mistake, taking into account what has already been written, is not checking for errors. This can take the form of spelling mistakes (remember the spell checker will not pick them all up!), grammatical errors or poorly formatted CV's. Take time to proof read your CV, before letting someone else proof read it. Sometimes the brain sees what it wants to see or what it should see, this makes you blind to some errors. Someone else will provide a fresh perspective and this will minimise the chances of any errors. The formatting may not be uniform which makes the CV look disjointed, so make sure that the CV is uniformly formatted across heading and text. Also, try to avoid inserting cells and tables if possible, as formatting can often change depending on the set up of a recipient's computer. Avoiding tables & cells will avoid the risk of your CV looking completely different to a prospective employer.