A common task in RDLC reporting is alternate row styling, here are the 3 most common types.
Regular alternating row styles
= iif(RowNumber(Nothing) mod 2, "LightGrey", "Transparent")
Alternating group colors:
http://bidn.com/blogs/briankmcdonald/bidn-blog/713/alternating-group-colors
Alternating group colors with alternating row colors inside the group.
http://www.bidn.com/blogs/briankmcdonald/bidn-blog/717/alternating-group-colors-and-alternating-row-colors