What are the main factors in SQL Server queries optimization?

AT A GLANCE:

Analyzing execution plans

Optimizing queries

Identifying queries to tune

The factors that involve in Optimizing Query in SQL Server are:

• Analyzing the query execution plan
• Minimizing the number of implicit connections.
• Eliminating the data reading.
• Getting rid of the procedural code.
• Excessive index fragmentation.

I think simply they are as the following:

1- Indexes.

2- Statistics.

3- Execution plans.

4- Query hints.