Here's a real easy bar trick:

With your fretting hand (Usually your left hand if your right handed), sound the open G string with your finger (fretting hand), Do a bar dive (Push your tremelo bar down at the same time you sound the open G String with your finger) then put your fretting hand over the 5th string harmonic area then bring your bar back up....makes a nice "Scream"....You can further make it cooler by shaking the living crap out of your bar after you bring it back up.

Another easy one is freting the 2nd fret of your open b string harmonic and your open E string 5th harmonic as a chord:

|-5-------------|
|-2-------------|

Then doing a bar dive.
Making the first harmonic on your B string (Second fret) takes a lot of practice and an extremely light touch.