Writing a persuasive essay should be easy. Understand the topic, take a stand, research about it, and present it in a way like you're trying to sell someone something. You should keep in mind that a persuasive essay is different than an informative essay. Do not just present information, compare them to others (kinda like "why should we buy your product" way of presenting things). Another thing is, always keep your essay cohesive. Do not jump from one idea to the other because that will not strengthen your argument. First present the topic, then present your thesis statement, then slowly build up your arguments making sure that these are backed up with facts, and then write a nice and concise conclusion. Always remember that the length of the essay is not what's important. Keep your essays concise and direct to the point, do not beat around the bush.