Hi KellyK, I am around the same age as you. I am a networker, who happens to do mostly programming for my company. Because of this I am like gold to them. I resently asked for a raise do to an increase in family size, and also the fact that people would ask me questions and how to do work whom happen to be on a higher pay grade than me. Of course, you can't mention that kind of knowledge to your boss.
As far as a percentage of income to ask for, it will depend on you. You have to ask yourself, What kind of lifestyle you want to lead? If you want a huge house with a new lexus and only make 25-30,000 a year, it will be difficult and you will probably be living ABOVE YOUR MEANS. Now, if you are between 90-100 then you might be okay. The key is to live BELOW YOUR MEANS and invest for the long road. There is nothing wrong if getting out the pen and pad and really trying to figure out what you need to be happy, facturing in your current bills, and what you plan to purchase. Just remember to always add a fudge factor in, say 10-15%, because you never know what can happen month to month.
In my case, I started out with a lower salary than I probably could have, but it seemed like alot in the beginning because it was and still is my first real job. I figured out what I needed to be happy and support my new family, and live a comfortable way BELOW MY MEANS so that I can retire a wealthy man. I asked for 20%, but remember that I felt that I was starting out low.
Once you figure out what you need to live happy, if that means a 10% then maybe ask for 15%, if that is 25% then ask for 20%, just make sure you give yourself some room for negioation. The worst that can happen is they laugh and say NO, I was thinking 10%. Then you plead your case more. If you don't find that you are satisfied, then just smile, and take what they give you in appreciation. Oh did I metion, since you sound as if you are good at what you do, you don't have to stay there. Remember that you HAVE A JOB RIGHT, so you can start resuming out for maybe a higher salary to see if you can get a bite.
Well, HTH, and sorry if I bored you with my rambling. - Mike