You can be apart of active support and not be violent. It's about turning your home ground into a fortress, it's about trying to give the players that little bit extra to get a win. Some groups are big on tifos and big flags etc, others vocally, and the best usually have both going pretty well.
A lot of say, the Italian clubs have strong political/religious ties because of the city or the people who started the clubs way back when. Some groups use this to push their own agendas though football, but it's pretty easy to ignore that.
Anyways, the best way they've discovered to do it down here is to get someone with a megaphone to lead the chants, probably a 1/3rd of the way up the bay facing away from the field. We've got a drummer too, but that's because we have alot more European-style chants which have more emphasis on rhythm than the usual English chants. It helps especially for the outer bays so they can sing in time with everyone else. But saying that, it's not necessary if you don't want one.
A few random things Sydney has done over the last 4 and a bit seasons.
[youtube]http://www.youtube.com/watch?v=4txucTDtZwQ[/youtube]
[youtube]http://www.youtube.com/watch?v=DlsbbCueOB8[/youtube]
It's also great for taking the piss out of your opponents (too big to post, click link)
<a class="postlink" href="http://img242.imageshack.us/img242/8086/wtde2and5.jpg" onclick="window.open(this.href);return false;">http://img242.imageshack.us/img242/8086/wtde2and5.jpg</a>
<a class="postlink" href="http://img529.imageshack.us/img529/6613/sydneyvmelb017uw3.jpg" onclick="window.open(this.href);return false;">http://img529.imageshack.us/img529/6613 ... 017uw3.jpg</a>
Here's a few from last weekend, pretty good effort considering it was 1000km away!
<a class="postlink" href="http://sfcu.com.au/smf119/gallery/756_08_09_09_5_27_29.jpg" onclick="window.open(this.href);return false;">http://sfcu.com.au/smf119/gallery/756_0 ... _27_29.jpg</a>
<a class="postlink" href="http://sfcu.com.au/smf119/gallery/756_08_09_09_5_22_36.jpg" onclick="window.open(this.href);return false;">http://sfcu.com.au/smf119/gallery/756_0 ... _22_36.jpg</a>