In very basic broad terms.. do any of you know of a guideline for exporting h.264 / mp4.

For example, I once found a very nifty .flv chart to which displayed optimal output setting depending on the input source / size etc required and using a chart displayed optimal setting.

Now there are litterally thousands of forum's as with posts on the internet and quite simply I'm bogged down with so many variables... it would be rather handy to have such a guideline available for the hd exports supported by youtube for example.

I apologise should this question come across way too broad, however would appreciate any comments / suggestions.
codecs / bitrate etc is a mind field... in an ideal world; wouldn't it be handy to have such a thing?

Best regards