So Bob, what exactly do you like to hear? Here's what turns me on about sucking cock...
A hard cock makes me wet...and the harder (not the size, just that it's hard!) the wetter...
I love it when I know a blowjob is just a blowjob...meaning THAT is the focus and I can do everything in my power to give a guy the best head he's ever had. (Don't get me wrong, I love to fuck, but just giving head is fun too!)
Personally, I love to try to deepthroat (I LOVE to gag on a cock!). Most 'normal' guys I can take down all the way after a few tries, but there have been a few big tools I couldn't get down. Once they start going into the throat, it's very hard to suppress the gag reflex and while I'm working on that (I practice as much as I can!), it's easy to go 'too far' and gag more than I (or most guys) are comfortable with.
When I'm sucking a cock, I don't need any warning that a guy is going to cum...it's not too tough to tell when you can feel him getting harder and the pre-cum increases. Once I know he's close, I like to grab his hands and put them on my head to keep me locked on his cock when he cums (yeah, I'm just a cum slut!).
I make sure I don't waste a drop...why suck a dick and not get the reward? ;-)
Hope that helped...and you can always come let me demonstrate in person! ;-)
Wow!! I think I need a few moments.