If you are focusing on using and/or implementing complex algorithms (i.e., not something like logistic regression/linear regression/random forests), an overview of the algorithms you will be using.
A description of your project plan, and an explanation of why the project is interesting and important.
An exploratory analysis of your dataset. The analysis should be driven and informed by
The grading will depend on the particular proposal (for example, not all proposals will include algorithm descriptions).
The following is a rough guide
50% of the grade will be allocated to your summaries of prior work. You should read, understand, and summarize roughly 4-5 papers (though this will vary from project to project)
25% of the grade will be allocated for a cogent explanation of the project plan
25% of the grade will be allocated for data analysis