There is a very lovely ritual of self-dedication in the back of "WitchCrafting," but it's. . . And you can use it literally, but it is there really more as a model. A self-dedication ritual is something that you should write yourself. It should be informed by your unique journey, the journey that you've taken.
If there is a deity that is called to you, you can dedicate yourself to that deity, and they will become, in effect, your spirit guide. If there is an interest that you have, it could be Green Magic, plants, or animals, or divination, whatever it is that calls, or women's mysteries, whatever it is that calls to you, you can dedicate yourself to that passion. That becomes your portal, or entry, into the realms of the sacred, so it's important to write it yourself.
The most important part of a self-dedication ritual, that you must write yourself, is your vow. You have to write. . . You can borrow from other people's methods and practices, but the vow is something that you should write and read yourself. It should be yours.