I have found site:reddit.com can be good to restrict results to a certain site. Inurl: if you know a bit of text in the url. Filetype:pdf can be handy if you on

I have found site:reddit.com can be good to restrict results to a certain site. Inurl: if you know a bit of text in the url. Filetype:pdf can be handy if you only want e.g. powerpoint presentations. Beyond that I think it is just knowing what things are called so you can search directly for things. For open directories you can use intitle:index.of last.modified booktitle