Standard & Extended Wylie diagrams Sambhota
DO NOT USE AS OF 2021
Just like Tibetans have used transliteration of Sanskrit words and mantras for more than a thousand years to write them in Tibetan script, it is often very useful to be able to spell and write a Tibetan word with Roman characters.
Here is the link to the Gerry Wiener's clear charts on how to read them and write them.
You can "right click" on each page to save it on your own computer.