Tuning MySQL server

After migrating the data from MaxDB to MySQL 5 [Ver 14.12 Distrib 5.0.62, for redhat-linux-gnu (x86_64) using readline 5.1], I've found our application's performance dropped a little bit. Now as every DB admin might do, I am going to start tuning the MySQL server. Here is my plan:

1. Get current DB status/parameters

2. Develop a benchmark suit before tuning

3. Set up a monitoring system to measure if my tuning improves or hurt the performance

4. Enable slow queries logging

5. Tune SQL queries of my app

6. Version control my.cnf and symbol link it.

7. Maybe, just maybe, order new hardware if necessary.