Hard to tell really, it just grows and develops. Each stage of learning is investigated and enjoyed, and then you find youself on a new level, and a new one after that. It just keeps going. You never stop learning.
I can still remember my first deck and being compleetly bewildered at trying to make sense of the cards. I found that trying to read the interpretations from a Sasha Fenton book such as 'a family event, a wedding or a party', a bit limiting in terms of interpreting a spread concerning the meaning of my life, or what my destiny is. 'A woman with auburn or red hair', isn't particularly helpful when you are inquiring about who the next male that you will encounter will be, or if you're enquiring about a past life in which you were black. You soon come to discover, that you have to make the cards, and their meanings your own. Learning by rote, though, is probably where you need to begin.
I think that I just bought lots of Tarot books, and you come to discover, eventually, that 90% of them are about the card meanings. Book after book, you come to learn the basic thread of meaning attached to each card, usually inspired by the imagery of the Rider-Waite-Smith deck. After a few books, you come to learn you don't need any more, they all say the same anyway.
Once I had come to this stage, becoming familiar with the divinatory meanings of each card based upon Colman-Smiths imagery, I began to explore Crowley's ideas which are very different. Then I came to see each card the way he saw them, according to his dictatorial correspondences. Then I dumped Crowley's messianic aspirations of world domination, and started thinking for myself. I must admit though, that it was Crowley that made me think for myself, because I thought, if he can do it, so can I!
Naturally, this caused me to wonder about my own correspondences, my own number symbolism, my own associations of elements with suits.
I began to forget interpreting cards based on someone elses illustrated portrayals, and began looking into pip cards, and interpreting cards based upon the symbolism of number in conjunction with the symbolism of the suit - and finding that the significance I would attach to many of the cards, didn't seem to relate at all to Colman-Smiths imagery.
Soon, I had my own keywords and astrological correspondences, which I would see in my minds eye when I interpreted the cards, regardless of the deck I used and it's imagery - the cards and their interpretations started becoming all my own.
Now I believe that although it is an incredibly tempting exercise to correspond the 22 planets and signs to the Majors, it is not possible to do this to satisfaction, and is in fact limiting your interpretative possibilities of the cards, rather than enriching them. I came to discover that keywords are also limiting, just as much as illustrated Minors are. All these things are very useful to beginners however, so look into them, and then inevitably, you'll be inspired by your own notions.
The stage I am at now, I am starting to believe that less is definately more with Tarot. The less correspondences that are dictated, the less keywords, the less someone elses illustration adorns the Minors, the great deal more I get out of a reading, so much that I would have overlooked otherwise.
This is not to say that I do not use decks with illustrated Minors, or keywords, or symbols because I do - it is just that these adornments are irrelevant to me as I read in my own way in my minds eye. The cards are simply to look pleasant, for me or the person I'm reading for, but what is on the cards no longer has much effect on me, it all about what's going on on the inside of my psyche rather than what's layed out on the table.
I think with learning Tarot, that's what happens - first it's a collection of puzzling pieces of artwork on a table, until it becomes internalised, and then it doesn't matter what deck you use - that's when the magick happens.
Just read and practice. Lay cards out again and again in all manner of patterns just for the hell of it, experiment, play with them. Note down ideas. Think of names for each card, colours for each of them. Think up your own correspondences. Fish for other peoples ideas. If you want it, and the cards want you, you will master the Tarot.
I am still learning, always will be, I have no idea where the journey will take me next.