Many folks are cautious about posting on the internet. More are not. True to Navy form, there is in fact guidance on how to properly post on the internet. It's from Big Navy's Public Affairs department, and its a very easy read.
You can download the PDF here
The twenty things you need to know before posting on the Internet:
1. You are personally responsible for your actions
2. Don't break the law
3. Identify yourself
4. If you wouldn't say it to your grandma, don't post it
5. Avoid spillage
6. Protect your privacy
7. Protect the privacy of others
8. Don't break the law
9. Use DON graphics as appropriate
10. Don't share information that is not approved for public release
11. Talk about what you know best
12. Correct misinformation politely
13. Don't get political
14. Look out for bad guys
15. Use strong passwords
16. Don't grant access to people you don't know
17. Choose applications wisely
18. Check privacy settings
19. Look out for intruders
20. Use anti-virus and anti-spyware
So just remember: