A great Personal Statement/SOP should have about 5/ 6 paragraphs.
Paragraph 1: Introduce your problem statement and connect it to why you want to study that course.
Paragraph 2: Talk about your educational background, your undergrad research experiences, and how they have...

prepared you for the proposed course.
Paragraph 3: Talk about your leadership, volunteering, and other extracurricular activities. It will be good if these experiences are connected to your intended course

Paragraph 4: Talk more about your research interest and mention the supervisor you have contacted(This is very important). Explain why you want to work with the person. Be specific about your research interest.

Paragraph 5: Talk about the University and why you chose it among other Universities, and what you stand to gain and contribute. Find out what happens to Alumni of that University.
Paragraph 6: Talk about your immediate, short, and long-term career goals.

Make sure anyone reading your SOP can understand WHO you are without the need to ask further questions.
Your SOP is your voice.