How to write a good persuasive speech?

I need to make the one for my college studying, I've never made such type of tasks, what are the most important things for it?

 

Didn't your professor/teacher explain you how to make the one? Also for what subject do you need to write it and what's your topic? It's really hard to recommend you a certain tutorial without knowing these details.
In general for writing a good persuasive speech the most important things are:
- choosing a topic (it should be a controversial one for creating heated debates)
- having a solid knowledge of the subject about which you would like to speak
- knowing main pros and cons of the topic
- understanding specific features of your audience
- grasping obstacles that your audience face with the topic
- presenting your strategy for eradicating the obstacles (you should have a plan in your speech for this)
- preparing a proper conclusion for ending the debates
- proofreading of your ready speech firstly on your own, then with a help of your parents/friends/professional editors papercheap.co.uk/homeworks for defining all mistakes/weak parts, including the ones which aren't noticable for you
- rehearsing your speech at home before your classes (very well if someone can listen to you while you're practising)