just soak it in for a bit is by best advice. Observe what is going on and what is said, sang etc. I wouldnt recommend a Vuvuzela lol. And refrain from any form of racial, ethnic, or even gender, or preference slurs. Those are prohibited and will get many people pissed off and jump down your throat.
I wish I would have had the following links before my first match, they would have helped tremendously.
Here is a basic chant sheet.
http://www.timbersarmy.org/wp-content/themes/ta_org_v1/downloads/TA_Chant_Sheet_2010_v4.pdf
Oh and learn the tetris theme, it is the most fun song EVER!
The following link is one of youtube clips for some of the chants, to help you with tunes and stuff. Youtube will help a lot too, if you just type in Timbers Army.
http://timbersarmychants.blogspot.com/
I wont be at that match unfortunately so I cant come and say hi. Just remember the Mottos of the TA and you will be just peachy.
"If you want to be in the Timbers Army, you already are" and "Spread the Love"
We are there to sing and stand and wave flags for the full 90 Minutes. So Just be ready to help pour your hearts out, and raise your pints, to the lads in green and white
105 is a good section to start out with IMO (I started in 108 first match, migrated to 106 and eventually found a home in 105) Its a little more laid back there.
Oh and lastly... Dont throw S*** on the Pitch