Howdy ficlite!
Redwood is right..there are so many different oracles out there(I have about 50 or so in my collection)...and so many different ways to approach the creation of one!
I would think that the first thing you want to do is decide how you are going to use it....do you want an oracle that tells the future? Or one that delves into your psyche, and dreams...or perhaps one that helps open your psychic center, and enhances your intuition?
Then decide if you want a theme...maybe animals that you meet each day, or a deck full of your favorite things, and images.
One of my favorite oracles, is simply a deck full of words. Things like.. "Creativity" and "Forgiveness"...it's one of the most usefull decks that I have for readings for myself.
But if you want to draw or create an image deck, then a good idea is to find a good book of symbolism...or begin to create your own symbolic meanings for objects and images that have relevance for you.
You can base an oracle deck on almost any existing divination system as well. A book on cartomancy... playing card meanings...can help! Or base a deck on the meanings behind certain crystals, or colors. I based a set of oracle stones on planetary influences, that came from a book about talisman making!
There are some great Oracles out there, from Parlour Sybil decks...to the Gypsy Witch decks...to the more advanced type...like the Faery Oracle and Medicine Cards.
I hope some of this helps stir those creative juices for you!
Good luck with your creation!
And above all, do whatever feels right to you!
Peace and Starlight,
Chronata