Know what's required from the outset
Before dedicating a large period of time to your CV, you should make sure that the recruiting organisation actually accepts CVs; while this may seem obvious, many people fall at the first hurdle as some organisations only accept completed application forms to facilitate their selection processes; thereby facilitating more direct comparisons between candidates.
Where CVs and covering letters are required, make sure you abide by any stipulated restrictions on length or content. Try to think of the time spent on the covering letter and CV as an investment to help you to get an interview and for your future career; this investment in time can also help you to build the foundations of your interview strategy. There are no black and white rules when it comes to CV construction as it remains an essentially subjective process. There are however a range of useful hints and tips that you can consider: