One technique that has worked for me is using indexes wisely. Indexes can significantly speed up query performance by allowing the database to quickly locate the data you are searching for. However, using too many indexes can have a negative impact on performance, so it is important to find the right balance. Another technique that has proven effective is optimizing the query itself by carefully constructing the SQL statement, making use of joins and subqueries in an efficient manner. I've also had success with strategies such as creating materialized views or using caching mechanisms to avoid redundant and resource-intensive queries. Overall, I find that a combination of thoughtful indexing, query optimization, and caching can greatly enhance the performance of SQL queries in large-scale databases.