1. FONT FAMILY
You can't substitute Segoe UI with a custom font family.
Do use the default font family, Segoe UI.
2. FONT WRAPPING
You can't show more text than fits on the tile by changing the wrapping of the template.
Do wrap text according to the layout of the template being used.
3. FONT COLOR
You can't use multiple colors.
Do pick one color for text on your live tile.
4. FONT SIZE
You can't use font sizes other than the defaults.
Do stick with the template's default font size.
5. FONT WEIGHT
You can't customize your tile with different font weights.
Do use plain text.
6. PEEK OPACITY
You can't use a transparent background.
Do use an opaque background for your tile's peek.
Don't include your app's branding (name or icon) in the lower left corner if it's already featured in the tile.
Do feel free to include both your app's name and icon in its live tile.
8. ICON SIZE
You can't use a larger icon size, even if the layout of your file has room for it.
Do stick with a default icon size of 30x30 pixels.
9. TILE LAYOUT
You can't create your own custom templates by modifying elements of the existing ones.
Do stick with the live tile templates provided in Windows 8.
10. OPPORTUNITIES FOR LIVE TILES
Don't miss out on opportunities to bring users back to your app by only providing a single default tile.
Do create beautiful live tiles that make sense for your app.