David Cameron used contrast, between other devices, contrasting the
"Road to ruin" the others will lead, and the "Road to prosperity" his party will lead. He also spoke lots of time about "Change" and "New", giving a special small favour to married people, and excluding all others, is it a "change" and "new"?
Gordon Brown, used also a contrast, a message that got also showed from the beginning, opening with the cabinet near him, and all through the campaign, asking others to come and speak with him, and thus become more then just a rhetoric device.
"I am not a team of one. As everybody can see, I am one of a team."
I do not vote in UK, but look, ponder. Think. Learn. Looking to speeches in this election, and analysing their impact, I learn a lot about how to become an effective speaker.