First of all mention your name, address and contact number.After you have written down the date, you can move on to the body paragraph that contains your intention to apply for job. Things you would state include your objective of joining the company? How can you enhance company's productivity? What is your previous experience in the field you are applying for? What is your academic background and how it can help you in your job? Lastly you can list down basic skills and experiences that you have attained from previous jobs, if any.
State that, no binding contract is to come into effect, except to the extent set out in the letter and that neither the letter nor any work done or payment made under the letter shall be deemed to be a waiver of the requirement to provide a binding contract. Finally, every effort should be made to finalise the contract as soon as reasonably practicable after the letter of intent has been signed.