There's no instant or magic way to build this kind of knowledge. It takes a long time. I'd add getting a copy of the book T-SQL Querying Fundamentals by Itzik Ben Gan. It's a great way to learn.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning