Drafting your Statement of Purpose should be considered to be, essentially, a communication exercise, which you ought to take very seriously. Why do we say this? Well, for two reasons: first, going forward, there will be many such situations in which you may have to interact with others by means of the written word. And second, subject-matter knowledge is not enough. You would need to find an effective way to communicate your message so as to evoke the desired response from its target reader(s).
Below are a few tips to draft a decent SoP: