DrDoc - 4:13 pm on May 3, 2013 (gmt 0)
You can always use UNIONs and subqueries to determine the order in which queries are run and JOINs applied.
Subqueries run before outer ones (obviously), and queries are executed in order of appearance for UNIONs.
That said -- even complex JOINs on very large tables run fast ... if indexes are carefully applied, and sometimes forced. (May need to ANALYZE TABLE from time to time as well.)
What does EXPLAIN tell you?
Many times you will find that the query runs just fine with the JOINs, but that it's your WHERE or an ORDER BY that messes things up.
For complex queries, consider limiting your result set through JOINs in a subquery, the apply all the ORDER BY and GROUP BY in outer queries, along with appropriate WHERE statements.