I was there during the 2005 Apertura and went to La Bombanera to watch the Boca versus Rosario Central match. luckily both teams where blue and yellow, so I had no problems blending in either way.
I bought tickets in the top stands above the fanaticos behind the goals, and the stadium fully shakes when they go up and cheer and shake the place down, so hold onto your seat
Wait until most people have exited beffore leaving the stadium as it is a mad crush into and out of this ground, and I mean CRUSH, so just be patient.
Oh, and don't wear a River Plate shirt there whatever you do, other wise risk being killed (no jokes here). I'm a River supporter with a River shirt but I went nuetral.
I'd recommend also River Plate matches, far more controlled (that is if you're not a Boca supporter), but there are fanatics there as well, so be careful. I remember when River beat Independiente at the match i went to, and theey had to call in the fire dept to put out a fire in the stands started by the Independiente supporters! Tickets to River plate from memory were also quite a few pesos cheaper.
"Coca Coca!!" make sure you buy your coca cola at la bombanera. If you've never been, you'll see what i mean