The Triskele Celtic Tradition has several steps in it's path. The following is a listing of these steps, and what is required of the person interested. As well, you may want to check out the Triskele website .
When you move from the homepage on to the index, there is a page named Triskele Celtic Tradition which outlines the course for the first year dedicate.

I will describe the generalities of what I have learned of these phrases, and then I will go on to describe precisely what the Triskele Tradition believes and teaches. This part will be in red, in order to separate the two.

Dedicate : This person is usually someone who has spent some time reading up, or learning in other ways, about paganism. They feel this is the path they wish to take in their life, and begin looking for a teacher, or a mentor. The prospective dedicate takes a look at what each Tradition may hold for them, and upon choosing the Tradition that suits them, takes a further look at the Deity or Deities. They may choose to dedicate themselves to a pantheon of deities, or perhaps just one or two. Some even dedicate simply to the Lord and Lady, thereby encompassing all the Gods and Goddesses. They then will do a bit of reading, or discussion with the teacher/mentor on the basics of pagan Ritual. At the proper time (being when the Dedicant feels him/herself to be ready) a Dedication ceremony is performed.
Triskele Tradition follows those steps, but supplies the curious with a reading list, and asks that the dedication ceremony be written by the dedicate. As far as the Trad is concerned, if the student wants to stand in the sun and tell the deities in his/her own mind, silently, what his/her purpose is, that is fine.
THERE ARE VERY FEW RULES TO FOLLOW IN THE TRISKELE TRADITION.
The student, after having read the books, and performed the dedication ceremony, is given a set of lessons every two months, along with a reading list, and other information. This will teach the basics of the craft along with some Eclectic additions. Depending on how the teacher and the student feel, after a year and a day of study and practice, and the student is ready in his/her heart, they can move on to the initiation ritual.

1st Degree Initiate : After having spent a year and a day as a dedicate, the student may now choose whether or not they are ready to move on and Initiate. This is usually a joint decision between the teacher and the student, or in the case of someone learning on their own, if they feel in their heart that they are ready. Once the initiation ritual has been completed, the student generally is given more access to the various rituals and spells that a dedicate is not ready to use. Quite often, it is recommended that an initiate must first be able to control their own personal power before attempting any larger scale spells, as they will have gained the experience to make less mistakes, and have less `blow-back` from spell and ritual work.
Anyone initiating into the Triskele Tradition must be able to control their own personal power. In this I mean that they must be able to control their emotions and the amounts of energy both placed in a spell and ritual. They must have completed the first year of lessons to the high priest(ess') satisfaction before being initiated. Spells become more detailed and are often required to be written by the initiate himself or herself.

2nd Degree Priestess/Priest : Generally, a student does not move on to 2nd degree for at least a year and a day, if not a great deal more time. Some, feeling quite comfortable right where they are, never move past this stage. In this stage of growth we find an initiate who is very capable in both spell work and rituals, and feels ready to move towards helping others through counselling and healing work. Occasionally, the new priest(ess) is given the opportunity to teach and have some control over the general management of a coven or circle. A 2nd degree priest(ess) in the Triskele Tradition will be expected to hold a circle for any magickal or healing work that is needed, and should also be able to teach others. The priest(ess) also has the right to dedicate a student if there is someone interested, and will then guide that person through the next stages. Until such time as there is a 3rd degree High Priestess/Priest in the Triskele Tradition, the priest(ess) may also be required to initiate a dedicate to the 1st degree. However, a High Priest(ess) is the only one with the invested time and power to initiate anyone to 2nd or 3rd degree.

3rd Degree High Priestess/Priest : A 3rd degree High Priest(ess) usually does a majority of the work involved in coven life. He/She teaches, counsels, takes charge of festivals, rituals, and group spellwork. Generally, the High Priest(ess) has the coven Book of Shadows, and from what I understand of this ranking (I am not as of yet 3rd degree), he/she is the "mother"/ "father" of the coven, or circle. Now, if it is a High Priest or for that matter, both of them, it would be "father" and "parents"! What I am hoping to achieve for Triskele in becoming it's first High Priestess (somewhere in the next five years!!!!) is that we have a happy circle, one whom the members feel is a family. A high priest(ess) ought to be able to provide this for his/her charges, if he/she is there when they need a hug, a laugh, or just to talk. He/she provides the foundation on which solid workings, rituals and circles are held.
When someone needs a hand up, or a hand to hold, he/she will be there. I also want to make sure that the Eclecticism in the Triskele Trad stays true to form. By this I mean, if it works for you, and it harms none, do it!

As to what each individual dedicates or initiates to, is entirely up to the person in question. The only true way I have found in answering this question is to use my self as an example. I am dedicated and initiated into the world of Celtic Mysteries, Myth and Magick, with my own stamp on this being The Triskele Celtic Tradition. I dedicated myself to the entire Celtic Pantheon of Gods and Goddess' although I generally work with Rhiannon(Welsh Goddess), the Triplicity of the Morrighan(Irish Goddess'), The Dagda(Irish God), and Lugh(Irish God). I invoke any and sometimes all of these deities during a ritual or circle.
And, I also invoke the God or Goddess I feel best suits the purpose of my workings.
I am not entirely clear on how many of the Wiccan Traditions have their covens or solitaries.

This article is from my point of view, that of a Celtic/Eclectic witch.