The 'book' says the fan should push the warm air at the ceiling DOWNWARDS in Summer. And in Winter, it should draw cool air UPWARDS. However, it can depend on your ceiling height or even how dirty/dusty it can get in the house.
For example, in Winter, you may actually COOL the house quicker by turning on your fan. Then again, maybe not. It's something you'll have to play with.
If your ceilings are high (cathedral-like ceilings), then all the warm air up there should be circulated (in the Winter direction I initially stated.)
Now, if in your home you happen to burn candles a lot, you'll probably see soot marks all over the ceiling after the Winter is over (because the fan is blowing/sucking UPWARDS in Winter.) If your ceiling (or house for that matter) is 'damp' or has a high level of humidity, moisture will condense on the ceiling and dust will stick to it, and build up, quicker than if you didn't have the fan on.
So you see, it depends. In my home, where we have 8' ceilings, we only use the fans in Summer (blowing downwards.) Be SURE your blades are not installed UPSIDE DOWN. Sorry to make such a simple question that much more complicated but others may benefit (or actually figure out why their ceilings are 'dirty'.)