What are best practices for creating, maintaining, and storing a will for legal action upon death?

Your will is a basic estate planning document that directs the allocation of your property upon your death.
If you are active duty, guard or reserve you can go to the JAG or legal aid and have them completed for free and this document is great for most people. If you have a more complex financial or family situation then you want to seek an attorney specialist in estate planning and trusts.
When the will is created, you should sign and have witnessed three originals. One kept by the attorney on file, one you store in a bank or off site lockbox you and your attorney know and one for your records.

Maintaining a will means as you have children or change spouses you destroy the older documents and replace with the new will.

Upon death your attorney will execute on your intentions as stated in your document.
Unless something in the will is deficient or an asset is acquired that stated which may involve the probate Court

We had JAG do ours way back when I was Active Duty. After 30 some years we decided to have new ones done since we figured the old ones were out of date with Info. The atty. we went to informed us there was no need to have new ones drawn up. The military office that had drawn our originals up had done an extremely good job .
A fire proof safe was the recommendation for storage, By our atty.. We were told NOT to put it in a safety deposit box. Reason being is that it will be sealed upon your death and not unsealed until the court proceedings.

I would seek help from an expert when drafting it. I would also review it at least once a year as well as within a few weeks of major events in your life. A lot of people store theirs in a fire/water/gun proof safe while others store it in a safebox at the bank. That said, the main thing is keep it somewhere that it isn't likely to perish when you do and to make sure somebody or multiple somebodies know where to find it if/when they need to.