Material in your sandbox is still subject to Wikipedia’s policies, so do not copy and paste information from your sources into your sandbox.
Start by taking notes of key concepts, not phrases, from your sources, noting where each came from.
Write the draft from your notes rather than from the original source, so you are not unconsciously mimicking the original author’s structure or diction.
The more sources you use, the better you’ll understand the topic, which can help you paraphrase and summarize it in your own words.
