Your CV should be split into two defined areas-Personal Details followed by your Career History.
If your career has spanned a long period of time, employers will want to see the most detail pertaining to recent positions. Summarise earlier positions to show career progression.
Keep qualifications to your professional qualifications and highest academic qualifications. If your career has only been for a short period, you are a recent graduate or a school leaver then ensure that you have a good balanced overview of your qualifications and achievements.
You should always ensure that you adapt and tailor your CV for the position that you are applying for. There may be some of your skills or experiences that need to be highlighted and shown more because of their relevance to the company, the role or the sector.