Read the publication, tailor your pitch to its audience and explain clearly to the journalist why their readers will be interested. Remember, the journalist's job is to interest readers.
Keep it concise and focused. Remove the waffle, especially unnecessary adverbs and over-blown hype.
In a written pitch, eliminate all the basic errors of spelling, grammar and fact. These distract the reader and make them question your credibility.
Don't be overly familiar. You don't need to call a journalist 'Mr Smith', but 'John-boy' is simply inappropriate. 'John' will do just fine.
Have an interviewee available for comment. Journalists get very frustrated with PROs who cannot deliver on their promises.
Know your pitch inside out. You don't want to get caught out by the basic facts.
Don't see pitching as an unpleasant task to be foisted on to the office junior. That will simply result in demotivated staff, alienated journalists and a failed campaign. Instead, resolve to lead from the front, shaping, delivering and honing the pitch yourself, and inspiring your junior colleagues with your successes.