Thesis Proposals
A thesis proposal needs to state the research question(s) you are trying to answer, the significance of the problem, the work that others have done, the work you have done and the approach to the problem. A good strategy is to follow NIH proposal format (Specific Aims, Significance, Preliminary Work, Research Plan).
Web sites that explain how to write a proposal
Some may not be related to your field, but all contain good tips on writing a successful proposal.
http://www.meaning.ca/archives/archive/art_how_to_write_P_Wong.htm
http://researchproposalguide.com/
http://www.eastchance.com/howto/res_prop.asp
http://www.ninds.nih.gov/funding/write_grant_doc.htm
Grant writing resources from NORDP (link)
An excellent set of resources is posted on the UMN Office for Vice President of Research site
http://www.research.umn.edu/advance/proposal.html
Some tips
Explain clearly the current state of knowledge, the gaps and how your work will fill the gap
Explain in some detail how you will conduct the research
Provide a time line. Last date on the timeline is the date you plan to defend (month, year). Take your best guess.
Create a dummy figure showing the data plots that you would like to show in your completed thesis. This will help you to think about the research methods.
For use of English, see Chapts 32-34 of RA Day, "Hot to Write ande Publish a Scientific Paper", 5th ed.