After working so hard to learn all 78 card meanings (and reversals, if you're down with that) and what they mean in each position AND in relation to other cards, it's really easy to get into a rut with your readings.
After you're comfortable, I encourage you to completely make up spreads, do readings with on card or thirty, and shuffle mid-reading just to see what happens.
I used the Celtic Cross spread for at least 15 years rigidly. Then I started reading it sideways. I don't know why - it just made more sense that way. Then I turned it into an upside-down pyramid with little pyramid spinning away from it. I have no idea what my readings will look like in the another 1 5 years, but I hope it's entirely different.
First you learn how to read the cards, then you learn how to play with them