Keep it short. Your CV should fit on one or two sheets of A4, so write concisely and be shrewd about cutting fluff. The chairman of a bank will be too busy to care about your GCSE in woodwork.
Know your audience. If you're applying for a variety of jobs, don't send a generic CV - talk up the skills that pertain to the post. Summer jobs and university activities smack of desperation, unless you're a first jobber.
Don't lie. Fabricate your degree and you risk losing any job you might land - as happened to NHS executive Neil Taylor in August. But let employers infer shortcomings - don't help them by stating anything negative.
Be specific. Don't just mention that you 'worked in a team'. State your achievements and quantify them. How many staff were you responsible for and how big was that budget?
The CV is only half of it. The covering letter is your chance to address the employer directly. Reference the parts of your CV that relate to the job ad and show the management that you tick all their boxes.
Check it thoroughly. Any careless slips in grammar and spelling, and your CV will go straight in the bin.