The Aces occupy an odd position in modern practice, and the oddity comes from a collision between two systems.
In the game, an Ace is simply the low card of a suit, or in some tarot games the high one, depending on the suit and the local rules. It carries no special significance and there is nothing to interpret.
In the Golden Dawn system the Aces are something else entirely. They are placed at Kether, the first sephirah, and treated as the root of the powers of the element rather than as ordinary cards. An Ace on this account is not the smallest instance of its suit but its undifferentiated source: not a specific fire but fire before it is anything in particular. That is why occult descriptions of the Aces read so unlike descriptions of the numbered cards, and why they so often refuse to say what the card means in practical terms.
Practical cartomancy went a different way and reads the Aces as beginnings, gifts and openings, the suit's business arriving. This is a much older and more mundane tradition, closer to the cartomancers of the eighteenth century than to any lodge, and it is what most readers actually do at the table.
Both are in use, usually at once and without anyone noticing the seam. A reader who says the Ace of Wands is a new venture is doing eighteenth-century cartomancy; a reader who says it is the root of the powers of fire is doing 1890s Hermetic Kabbalah. The two do not contradict each other, but they are not the same statement and they came from different places, roughly a century apart.