Keep it simple, 'Yours sincerely' if you began the letter "Dear Mr Jones", "Yours faithfully" if you began "Dear sir"

Put the letter on top of the CV and put them into a plain envelope without folding them more than once. If the pages are folded they are difficult to photocopy, and look untidy.

If you are making a speculative approach, it is a good idea to follow up your CV with a phone call to ensure that it has been received and to show your enthusiasm.