Like working with any Spirit, select one deck and stick with it for some time. Don't go from one deck to another, to a third, to a fourth and so on. It takes time to get to know it. Most modern decks are merely stylistic variations of the Rider-Waite deck anyhow, which itself is heavily influenced by both the older Marseille in the Major Arcana and the Sola Busca Tarot in the Minor Arcana.
There are many things, in my opinion, that the Golden Dawn did not get quite right, but the Tarot was one of the few things they did really well.
So the Rider-Waite is a solid contender.
The first thing you ought to consider is the proper consecration of your deck which is the difference between having a set of plastic cards versus a proper magical tool. Given that the Moon in Neoplatonic thought is associated with the World Soul and is said to rule generation and corruption on this our Earth, it falls well to consecrate it under her aegis. Select the day and hour of the Moon (Monday during dawn) and fumigate it with an appropriate incense (such as Jasmine) and utilize either the Orphic Hymn to Selene or the Picatrix's hymn to the Moon while facing the East.
Sleep with it for a couple of days afterwards before taking it into use. The idea, from Daoist Feng Shui thought, is that there is a threefold division of the Qi of Heaven, Man and Earth. By consecrating it to the Moon, you will have imbued your deck (Earth) with a celestial power (Heaven), and now you want to link this deck (Earth-Heaven) to yourself (Man).
Store it accordingly in either a tinbox with some consecrated salt or a piece of silk cloth, as you don't want any unwanted spirits influencing your readings.
Now. Where to start?
With Astrology.
This is important, because you will find a tremendous mountain of books dealing with the "explicit" meanings of the cards, which is to say their history and symbolism. However, by introducing the "implicit" astrological meanings, you are significantly broadening your vocabulary and allowing the Spirit of the Tarot to articulate it's intelligence with you in a much more meaningful and nuanced way.
This likewise goes for any spirits you may ask to speak through the medium.
The Rider-Waite ascribes the 4 elements, 7 planets and 12 zodiac signs to each of the cards of the Major Arcana. They are as follows;
Fool = Air
Magician = Mercury
High Priestess = Moon
Empress = Venus
Emperor = Aries
Hierophant = Taurus
Lovers = Gemini
Chariot = Cancer
Strength = Leo
Hermit = Virgo
Wheel of Fortune = Jupiter
Justice = Libra
Hanged Man = Water
Death = Scorpio
Temperance = Sagittarius
The Devil = Capricorn
The Tower = Mars
The Star = Aquarius
The Moon = Pisces
The Sun = Sun
Judgment= Fire
World = Earth / Saturn
The four suits are divided into the four classical elements;
Wands = Fire
Swords = Air
Cups = Water
Pentacles = Earth
Aces (1) are considered the "root" of the element.
Cards 2-10 are considered representative of the Decans, the subdivision of each Zodiac sign into 3 equal parts of 10 degrees. There is a Spirit associated with each.
Wands 2, 3, 4 = Aries
Wands 5, 6, 7 = Leo
Wands 8, 9, 10 = Sagittarius
Swords 2, 3, 4 = Libra
Swords 5, 6, 7 = Aquarius
Swords 8, 9, 10 = Gemini
Cups 2, 3, 4 = Cancer
Cups 5, 6, 7 = Scorpio
Cups 8, 9, 10 = Pisces
Pentacles 2, 3, 4 = Capricorn
Pentacles 5, 6, 7 = Taurus
Pentacles 8, 9, 10 = Virgo
Austin Coppock's "36 Faces" deals with the description of each Decan very nicely, utilizing sources such as Agrippa and the Picatrix, amongst others. It's a really solid book.
The Court Cards are considered elemental as well;
Page = Earth
Knight = Air
Queen = Water
King = Fire
So a Page (Earth) of Swords (Air) would be the interaction of the elements Earth and Air for example, allowing you to deepen your reading beyond just the superficial meaning of a man holding a sword in the wind - although at times, to be fair, the superficial meaning is indeed the intended meaning.
This is part of the learning process. Often times your cards will be correct, but your interpretations will not, and you will have those "aaaah, THAT'S what that card meant" moments. So do write all your divinations down in a book. You may think that your question is the most important thing in the moment and that you cannot possibly forget it, but life goes on and you will.
My own theory is that the Spirit of the Tarot is a very Mercurial spirit and has a trickster element to it. If you haven't thrown your cards in frustration across the room in utter frustration, you haven't been doing it long enough lol.
It's super adaptable in terms of signifiers and that is it's main strength, in contrast to systems like Geomancy or Horary Astrology, where the signifiers are very fixed. In Geomancy, for example, the first figure is always considered as a signifier of the 1st House, which is to say the querent. Whereas in Tarot, the first card can be anything you please.
Selecting the right signifiers for the Spirit to respond to is really the crucial thing. An example. You do a three card spread. That can represent the past, present and future. Can also represent the person and how they behave publicly, privately and secretly. Or, when you wish to identify someone, how they come across in their Ascendant, how they behave per their Sun sign and how their emotional constitution is per their Moon sign. And so forth. As long as you articulate it out loud to the spirit.
Don't look up fixed meanings online or in books, or have someone else interpret the meaning, because it will be, to a certain extent, catered to your idiosyncratic understanding. Somewhat. It's not entirely subjective either.
And learn a good shuffle. There should be some symbolism behind it too. How many times you shuffle, turn and break your cards. Some spirits, if you use it for that, seems to like for a card to "pop out" to get their message across. I've had a couple of times when I put it back in and continue my shuffle, only for it to appear again as the final card.
But yeah. To summarize. Consecrate. Store properly. Learn the implicit meanings. Be intelligent about assigning signifiers. (A short prayer before you shuffle to get you in the right mindset is a good idea that I forgot to mention). Make your shuffling ceremonially and symbolically meaningful. Note down your readings. Reflect and learn.
And don't see fate as something set in stone, but more like the current of a river that is prone to change