Permission modes

Been running into problems in WordPress with permissions.

I pretty much need someone to tell me what WordPress files need what permission modes.

I’m installing WordPress in my base directory (public_html for example), so should I change the public_html folder (and all sub-folders and files?) to permission mode 755 for instance?

I just want the site to be generally secure, but not run into any problems with permalink changing and general moving of files within my site’s directories.

Any help is appreciated. A point in the right direction would be great. Thanks guys.