There are a lot of things that you can add to your spiritual ethical will. The first things that you need to address in your ethical will are legal issues. You need to identify your assets and beneficiaries. This part is a bit dry and you may need the help of an attorney to put it together.
The rest of your ethical will is up to you. You can select what type of information you want to provide your heirs and what information you want to leave out. However, since you are writing a spiritual and ethical will you do want to provide some sort of written dedication or expression of what you felt your contribution to the world was and what your philosophies on life were. Many people who create ethical wills simply create journal type entries that address the issues that they felt are important as well as writing private letters to people that are important to them.
Another route that you can go is to include poetry that you enjoy in your ethical will. Your taste in poetry will most likely evolve over the years, so you may want to start collecting poems that you run across that you like now. Keep a copy of the poems you like with your will and the next time you revise your spiritual ethical will, work the poetry into its content.
Your spiritual ethical will is yours to design as you see fit. Include as much or as little information, letters, poems and other materials in your ethical will as you want. To ensure that your spiritual ethical will is manageable, however, try to edit the content periodically removing items that no longer are relevant.