Each card has particular symbolism in the Rider-Waite-Smith tradition, for example, the flower on the flag of a skeletal Death or a scythe. However, if you're making your own then you can include your own symbols if they say the same thing. The Shadowscapes card of Death is a phoenix, for example, and I think that's very clever even though it's not traditional.
So, in my opinion, you can feel free to play with the symbolism. There's a zombie-themed tarot deck out there that replaces the Pentacles or Coins with "Hazards" and that is very non-traditional, but I also think that works well with the theme of the deck. Life during a zombie apocalypse (replace that with any social, environmental, or economic upheaval) isn't going to be as stable as the Pentacles will symbolize, so it makes more sense to replace the suit of stability and resources.
That's for themes. Ink? I'd say whatever works.
They're not like runes that have an established myth behind them or galdhr traditions. I think it's more a matter of practicalities or intuitions than mystically following some precedent. Tarot is a fairly modern thing, that even the Golden Dawn adherents went more for an illustrator (for whose time, efforts, and talented Rider made no recompense, shame on the industry) and a publisher of cards. It's up to you, then, how you want to make your deck.