Artificial Flower Arrangements

Silk : These are good for imitating delicate flowers like roses. A new addition to this type is textured silks--perfect for hydrangeas and peonies. There are also matte-finish silks (they feel like dryer sheets). These can be printed on to highlight the veins of a flower.

Latex : This is a new category in artificial floral arranging and this material looks best when the flower it's imitating is tropical and rubbery-looking in its natural state.

Dried : These continue to be popular, too.
Tips:

It's okay to use all silk or all dried flowers in an arrangement, but all latex can be too heavy. Combining some with the other two adds texture and airiness.
Silk and dried flowers are always a winning combination.
Be innovate with the container--it can be half the arrangement sometimes.
There are sealants and preservatives for dried flowers to make them easier to work with and more durable. Cleaners are also available that dissolve dust on artificial flowers.
Look for artificial berries to use in arrangements, as well.