For example if a page has some .css, .js, .png files and so on, would loading the css first, display things faster?
And is there a standard/specific order to load file types?
Here are few steps that could optimize the performance of your web pages.
put css at top.
set far future expire header.
return 304 when appropriate.
use unique url for css and js for propagating the change.
apart from that use
ajax wherever required.