I am not sure if I understand the complete opening theory behind the Sicilian opening. But I do understand the opening theory in general. 1..e5 branches off into a variety of openings. So, if you want to limit yourself for learning purposes, c5 is a good choice.
In case you want to take your opponent playing Sicilian for a ride, you can try the Morra Gambit (also known as the Smith-Morra Gambit. There are also some traps available in the Morra.
I used to play the sicillian as black, until I learned, that I hadn't learned yet. I didn't understand all the theory behind sicillian and realized that I could never really punish my oppenent for not playing appropriately against it. I recenently started playing 1. ... e5! (!, but there are plenty of good defenses, I've just learned that e5 is a ! compared to c5 when you really don't understand the theory.) which has allowed me to better understand core opening thoery.(Control center, develop etc. etc.)
ANYHOO, I started making the realization today that it is very likely that many of my oppenents at my level, don't understand sicillian theory either. Both in Blitz(the few I play) and online, I see c5 on a semi regular basis, or e6 or something transposed. Is there any advice I can get on punishing this? Or does it really even matter? My understanding is that the opening is less and less critical the lower your rank(not less important, just less critical to the outcome of the game.)
Primarily I just wanted some thoughts on this... thought. :) Thanks.