Simple setup of sqlplus autotrace

Make sure the line size is long enough to diplay the output

set linesize 220
set pagesize 200

Turn autotrace on and only show the trace and explain plan
Dont show the result set of the query. Note the query will still be
executed

set autotrace traceonly explain

If you do want to show the result set

set autotrace on explain

You may now want to set timing on for simple wall clock timing

set timing on