Sorry for the delay. I've been busy with holidays, getting ready for grad school, finding a part-time job, and... yes, getting a bit of play in. (Oh, and Skyrim ate my life.)
Okay first of all, Oglaf is hilarious, bizarre, and gross (in other words: amazing) and you should read it if you haven't done so already.
I recently was asked by someone out of the blue what it meant to be a good sub. I was a bit blindsided because, well, I don't really consider myself one. I call myself one since saying "I'm a bottom" can just get confusing, but it seems that I fit the profile of a BDSM bottom more. Bondage? Pain? Hell yeah. But once I'm out of a scene, service and orders and chastity just don't do it for me.
That said, I did think there were two areas in which I think both bottoms and subs should keep in mind. Regardless of the amount of control you're giving to your top, you need to remember that it's not all about you. I always like talking before hand if I'm playing with someone new to see what they like. If they like getting their cock sucked, I'll suck their cock. If they like me wearing a football uniform, I'll do that. If they want me to call them Ronald McDonald, I'll... okay, there are some lines that shouldn't be crossed. Regardless, I do what I can to make sure they get a lot out of it. As the bottom, it seems like I'm the one who's taking (even though I'm giving up power) so I like to make things feel equal.
On the other hand, it is about you. If a top is doing something to you and you really can't handle it, tell them. Preferably before hand. I've heard of a few cases in which a top had been doing something physical or using verbal humiliation and the bottom did not like it, but didn't say anything until way after the scene. The best tops listen to your limits but encourage you to push them, but going too much over that is going to hurt you and will hurt their trust in you. (The nicest people I know are sadistic bastards in a scene, and I love them.) It's your responsibility to let them know when you know you can't take it.
I'm still not sure I gave the right advice for what someone asked, but this has been what has worked for me in the past.
Any more advice? I'd be interested to hear your thoughts.