Traffic
Not all tile is made equal. Some tile material is better suited for high-traffic areas. If you are planning on tiling a hallway, entrance-way, living room, or other high-traffic area, make sure you use Group V tile. Tile flooring is rated and characterized into groups; Group I - Group V. Group I tile is best suited for countertops, while Group V tile can endure heavy traffic and can be used almost anywhere.
Water
If you're tiling an area of your house that will see a lot of water (read: bathroom, kitchen, etc), you want to make sure you're using a tile that is rated as "impervious", "non-absorbent", and "non-porous". If you opt for a more porous tile in a bathroom or kitchen area you may be setting yourself up for some expensive repairs or replacement projects down the road.
Design
Not all tiles work best for artistic interior design projects. A creme porcelain tile might be just fine for a bathroom counter, but it might be a bit dull for an entranceway. Try livening up your tile flooring design with a textured or multicolor porcelian, or a patterned glass mosaic tile.
This glass mosaic tile would look stunning as a decorative entranceway or runner.