I've been working on optimizing my site and databases, and I have been using mysqltuner.pl to help with this. I've gotten just about everything correct, except for the table cache hit rate, no matter how high I raise it in my.cnf, I am still hitting about 0% (284 open / 79k opened).

My problem is that I don't really understand exactly what affects this so I don't really know what to look for in my queries/database structure to fix this.