The ancient Filipino script is called baybayin, also commonly known in the 20th century as alibata. Learning and writing baybayin comes easy, but going through its origin and history takes a lot more unraveling and analysis. So I won't go there on this book. I am almost certain that what caught your interest is the fact that Filipinos also has ancient writings and you want to learn how to use it... correctly ...without permanently inking it in a place you cannot erase or replace... so we'll learn more about the implementation of baybayin.
With this primer, you will be introduced to the proper reading and writing of the baybayin script yet also with the hope to inspire you to also know it's origin and history. Perhaps after gaining its roots, you will have better stronghold and pride in sporting every character of the ancient Filipino writing called baybayin. Have Fun!