the bulk of any intel gathering is done by OSINT methods; about 10-15% come from secret HUMINT sources; obviously that kind of intel is going to be rare. Agencies work hard to keep those sources secret to protect the flow of data
The bulk of OSINT is subject to Information War methods, and all HUMINT sources are as well.
get the data, sort for bias, analyze, then double-check and triple-check
it's never ending lol