The obvious requirements for a "SQL Server Developer" would be to know relational database concepts and how to write SQL. Start with a book on generic RDMS theory, data modeling, and straight SQL first. Next a book on SQL Server T-SQL development, and then a book on data warehousing implementation that covers topics like SSIS, SSRS, and performance tuning large databases.
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho