CHMod Guidance

Hi,
I’d like some guidance on how to chmod.

I followed this rule before “Directories should have permissions of 755. NEVER 777
All files should have permissions of 644.” for all files and folders in my wordpress directory.

Now my site can’t load its theme properly, I think (ispithotfire.com). If I want to start manually changing permissions, what should I start with so I can track the issue down (and what permissions should I try?)