Tarot cards have fascinated peoples of the world for millennia, and there are truly thousands of tarot decks to choose from. And that is why your knowledge is needed: Where do people start?
There is so much that you can talk about on a tarot blog that you will have a hard time narrowing it down.
The historical development of tarot cards is fascinating, how different decks evolved, and how they are used today. Be sure to offer lots of options on your blog, especially the hard to find decks.
Reading tarot cards is the most popular option for a tarot site, and if you are gifted in that area, do so. With all the live telecommunications available, it is so easy to set up a conference call with your client, no matter where in the world she might be. When you have a selection of decks for her to choose from, it becomes so much more interesting.
But reading cards is not the only option.
The tarot cards themselves are works of art. I once had a needlework company and one of my popular designs was taken from old tarot cards. I created the whole needlework kit with fabric and yarns and needles and sold them at a premium. You can do the same with crewel embroidery, counted cross stitch, mosaic, water colors, coloring book, iron on designs, stained glass, and any number of other creative arts and crafts.
Do write a book about reading cards, or set up a whole course on the technique. There are some pamphlets available, but a full, structured course would be so much more valuable to many. You can probably draw a lot from your postings on your blog for the content.
Create hand painted scarves or robes with designs from old tarot decks.
And if you are truly talented, create your own tarot deck, and build your whole site around that.
These decks have inspired millions over millennia, and they can inspire you too. Let your creativity flow!