Your resume is your salesperson. Long before you meet a potential employer in person or have an interview, your resume will be fighting for you.
So it is imperative that you create an effective resume. Your resume will be one of hundreds, if not thousands, that employers will see, so you should make sure it really stands out and promotes your services. The exact approach of your resume will depend on you and your circumstances. School leavers and graduates won't have much work experience to list on their CV. If you fall into this category, you should pay special attention to your academic achievements. Point out any other facts about your school life and the rest of your life that you can draw on when you get the job. If you have successfully completed work experience, list it and provide details of the tasks you have undertaken.
On the other hand, if you have gained your experience in the workplace and have few formal qualifications, you should use your employment history to your advantage. Talk about the roles in a little more detail and describe the tasks you've taken on. The more advanced or the more credible a particular role was, the more you should draw on it in your description. A highly effective resume will also include an accomplishment section with each qualification or job section that is relevant. You can include graduation, or you can include specific work-related accomplishments. Remember that there is a chance that someone else has the same skills or qualifications as you, but using your achievements as your main asset will still make you stand out and make a positive impression. Aside from your cover letter, your resume is the most important thing you have in your job search.