This is such a powerful question! Proper pay begins by knowing the local market value for what you do. This is not hard to learn. Google it. BLS.gov offers this information as well as several private sites I mention in the book.
Once you know your market value the next part of the calculation comes from (see previous question "How do I measure my performance...") listing your accomplishments and to the best of your ability, determining the value of those INDIVIDUAL, Free-Standing accomplishments to your employer. (Much of the book speaks to this issue!)
By adding up the value (to the company) of each of your accomplishments OVER AND ABOVE what is expected of you daily, over time you will see how you DO add value above and beyond what is expected of you that you are NOT being compensated for. Know that it is NOT the company's fault you are not being paid for this. It is not your company's responsibility to note your wins. (If that occurs, great! If not, shame on you.)(I tell the story in the book about how I, personally, saved a previous employer millions of $'s but got no benefit from it. That was MY problem for not  recognizing my win. Not theirs.) Again, there is probably an answer to this question in virtually every chapter of Leveling the Paying Field.