Accuracy and completeness are critical. If there are gaps where information has not been provided – or gaps between jobs or education that aren’t explained – then the person recruiting will wonder why. If they are busy (and they probably will be), they may decide that they can’t be bothered to find out and so your application goes on the reject pile.
Selling yourself well is also very important. Use the additional information section for this purpose, explaining what you bring to the role and why you are interested in the job.
I can help you produce your application from scratch or take the role of editor/proof reader, making comments and highlighting any errors in phrasing, grammar, punctuation, etc.