KeepAlive normally makes a lot of sense, requires more memory but lowers the number of connections, CPU usage and connections overhead. MaxClients and other stuff must be tuned to your situation instead. Normally you'll want Apache to have a number of idle instances big enough to serve all of your users without having it to spawn new child processes all the time; at the same time you want to avoid excessive values for maxclients in order to keep memory usage under control. Unless you have sudden usage spikes though, the default Apache settings are usually adequate and will self adapt well enough to your environment.
If you serve content through https and since you're not using php you might want to give a try to mod_spdy module too, many browsers support that already (waiting for a global support for http 2.0).
Finally another option is to use caching/precaching. In that regard some functionality is already available in Apache thanks to several modules (please see http://httpd.apache.org/docs/2.4/caching.html ), or you can put something else in front of the server (Varnish is a popular option).