Writing a good persuasive essay is largely

• overcoming fear
• believing in what you write
• and having the confidence to communicate in writing

Here are some strategies:

Think of the questions posed in the assignment while you are reading and researching.
Determine

• how the author's views fit into the questions
• what you think of the author's argument
• your position in the argument

Focus on logical argument and avoid emotion/emotional reactions or recognize those you have so that you may use them wisely.

Start writing!

• Start as close as possible to your reading/research
• "Jump in"; don't be afraid to start writing
• Jot down the succession of your thoughts
• Do not concerned yourself with grammar or spelling

When your first draft draft is finished:

• Put it away!
• Don't think about it

Review your notes and original material after some time has past.
Does your argument still "make sense"? Ask yourself:

• "Will my argument convince an objective reader?"
• "Will this paper ask someone to re-consider their position"?

Take up your paper again:

• Revise and edit the content to strengthen your argument
• Note where you use emotion to see that it doesn't interfere with the logic
• Correct for spelling and grammar
• Ask a friend to read it, and make suggestions for revision
  Ask them if they are convinced