Best format for SQL Server is 'YYYYMMDD', which is always interpreted correctly. Therefore, for literal dates, always use that format, do NOT do a CONVERT to a date/datetime type yourself, since you might force a conversion on the table column if it changes data type later.
If you need time also, you can use 'YYYYMMDD HH:MM[:SS[.SSS]]' where hh = 24-hour time.
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".