To start off, you must assess how much time your speech should take. It is better if your speech is short yet informative at the same time. Therefore, even if you have absolutely no restriction on time, make sure that your speech is short so that you can capture the attention of the crowd.
Think about the audience and while you are writing your speech, and let your perception of the audience shape up your speech.
Always start writing with an introduction where you can explain to the audience about who you are and what your purpose for being up on the stage is. People often include jokes in their speeches and that always ends up making a positive impact on the crowd.
Try to write down everything in points. Once you have done so, organize your information from most important to least important.
If there are certain points which you think are unnecessary or you believe they are not crucial for your speech, simply delete them.
Try to move from your most important point to your least important point and then move back to your most important point. For instance if you have ranked them 1 2 3 4 5 in terms of importance then move from 1 to 5 4 3 2.
You can always add support to every single point by using a stat, an example, a statistic, or even quotations.
Always link your introduction, your points and your conclusion. Make sure you are not breaking the three up or it will only leave the audience confused.
Lastly, always write a conclusion which summarizes each and every point which you have mentioned in your speech.