Start with the introduction. You do not need a title page or page numbers for a proposal in MLA format. The introduction should not be longer than one-third of the total length of the proposal.
Write a thesis statement for the end of the introduction, as well as an explanation of how you will approach the issue which you have brought up. Be concise and clear in your wording.
Write a small body paragraph --- approximately 3 to 5 lines --- explaining why your thesis statement is relevant, useful, and important. Provide solid factual information that backs up your claim. This section should be approximately one-third of the proposal as well.
Write the conclusion of the proposal. This should be the last third of the entire proposal. The conclusion should include information and implications that you will arrive at in your actual essay, as well as an any reasoning for this. Provide factual evidence for this reasoning.