You have already configured Apache to control the number of child processes to keep running. This directive will tell Apache how many to start initially when your server first boots. Depending on the level of traffic you expect to get, this number may be low or high. For general purposes, 5 should be sufficient.
This controls the amount of time Apache waits to do a number of tasks. For example, it controls how long it waits for a GET request (i.e. for someone to download a page or images) and also how long it will allow a POST request (i.e. when someone is sending something on a form). The default is 300, but you can lower it to something like 150 to help reduce some server strain when it is waiting on failed attempts and also help prevent DoS attacks on PHP scripts like message forums. Do not set it lower than 90, however, as this may cause some of your site visitors to get timeout errors on working content.
Once you have made all of the changes you want to make to your Apache configuration file (httpd.conf), you need to restart Apache:
service httpd restart
These tips are not the only ones you can use to optimize your Apache installation, but they should help you get a head start.