Having come up against the dress code issue recently - the standard advice is to make your best guess about the dress code hierarchy and dress one level higher

Having come up against the dress code issue recently - the standard advice is to make your best guess about the dress code hierarchy and dress one level higher than the job you're applying for. The covering letter should be seen as the chance to make an argument as to why you're the right person for this specific job. You shouldn't really have a template for your covering letter.