I've been running mysqltuner from http://mysqltuner.com/ for several months now and have been making adjustments. Running it is pretty simple. It gives a report with change recommendations at the end.

MySQL configuration file should be: /etc/my.cnf

Mine looks like this right now:
Code
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1

query_cache_size=256M
join_buffer_size=150K
tmp_table_size=256M
max_heap_table_size=256M
thread_cache_size=4
table_cache=450
key_buffer_size=512M

log-slow-queries=/var/log/mysqld-slow-query.log



[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid