Ways to Tune the Queries in SQL and Type of Indexes

There are many methods to tune up a query.
1) using EXPLAIN_PLAN.
2) using AUTOTRACE and set Timing ON.
3) tkprof
4) Indexes
5) Cost- based Optimisation
6) Analyze command.
7) parallel query option.

Types of indexes

B-tree
Bitmap
Hash
Index-organized table
Reverse key
Function-based
Partitioned (local and global)
Bitmap join indexes