While there are some age-old propaganda strategies -- dazzle the audience with statistics, encourage everyone to "jump on the bandwagon," scare everyone with dire predictions -- more people are aware of those tools today, and are less likely to to be impressed by them.
To convince someone of your point, (1) make sure it is accurate so that glaring mistakes don't immediately destroy your credibility; (2) back it up with expert and credible research results when appropriate to the topic; and (3) apply the points to the personal, daily lives of the audience. Avoid vague or altruistic appeals. Stick with the answers to: "How does this affect me? What's in it for me, if I do want you are proposing?"
Also, keep the message simple. Explain it concisely with a minimum of words. Present the facts and the action you want the readers to take, then stop.