Secret clearances aren't that big of a deal. I've even gotten a couple of temporary ones "interim" Secret clearances to work on some things or access certain facilities simply by providing Name, SS#, etc. and having a background check via computer done, with NO paperwork! Granted, those were not permanent clearances.
These certainly have changed over the years, for a TS it used to be a 60 page forum and they went back to birth. Yeah - people came out and talked to your kinder garden teacher. Also, no drug use was permitted - at all.
Looking at a Standard form 86, revised 1995 (so it may have changed post 9/11) and it's only 11 pages. Name, DOB, place of birth, SS#, aliases, physical descript, phone, citizenship, where lived for last 7 years and contact that knew you at any addy listed in last 5 years, where school post jr. high, but only last 7 years, if more than 7 years, only last., employment, 3 people who know you well, spouse, relatives and associates, citizenship of relatives and associates, mil history, foreign activities, foreign countries you have visited, mil record, selective service record, medical record, employment record, police record (felony, firearms/explosive, pending criminal charge, alcohol or drug, uniform code of mil justice, any other except traffic), illegal drugs since age of 16 or last 7 years, alcohol, prior background investigations or clearances, financial record, financial delinquencies, public record civil court actions, association record (member of group advocating the violent overthrow of the united states), auth. for release of medical records.
This form is a total pain if you have moved a lot and had roommates...
Tolerance of drug use varies - ie: CIA, smoked pot more than a year ago and not a current user is fine, while NSA has no tolerance for drug use. Likewise, CIA is more uptight about associations with foreign nationals, while NSA says they are OK so long as they are not "close and continuing". At higher clearance levels ALL foreign travel has to be approved in advance also you loose your right to write for publication without pre-publication review. (higher clearances only)
There are some supplemental forms depending on what you are applying for.
then personal interview
and if a high level clearance: polly, psych, physical.
Things they REALLY care about:
If you lie to them about ANYTHING! - don't worry about it - they have heard everything.
Felony convictions.
Poor financial history (people that need money are not the best to entrust with sensitive info)
Foreign entanglements.
if you are reliable, trustworthy and of good character.
What they really don't care about:
drug use in your distant past.
political activity
your sex life (but they do want to know if you will lie about it! - polly only)
-t