It is widely known that heat travels up and hot air contains moisture, which means that in a home, heat and thus moisture travel up into the attic.  Articles for Insulate Now, and many other magazines and government programs, have encouraged home owners to make sure insulation levels in the attic are at least at current code levels, but before you get around to it, we suggest one simple thing that you should do to save you a headache: make sure your eaves are not blocked and air can circulate.
The last thing you want is water condensation in the attic.  Any condensation on the floor of the attic will accumulate and freeze, and will wait to thaw out in the spring and leak into your living area.  To avoid this, you should head up to the attic to check that the eaves are not blocked and air can circulate.  This will carry moisture out of the attic, and as a bonus, there will be less fungus growing and rotting of your roof.
Cost of materials to do the above – ZERO!
Furthermore, while you are up there, if you see any insulation out of place, you can even it out.  Hopefully seeing your attic will make you realise that fixing breaks in the ceiling air barrier and adding insulation really is not that difficult!