Here is how I break it down.
1. Cost of living increase
2. What you are actually worth
3. Premium for doing something more difficult, dealing with a new/difficult company or manager
4. Increase as a result of you being kickass, learning both educationally and on the job
COL is easy to figure out, salary.com shows increases between living areas
Salary.com also shows positions like yours, or you should have a general idea how much your position should be worth relative to what you are getting paid now. Most companies give you smaller raises and eventually pay you less than what they would pay somebody new, because they can get away with it
Always include an a-hole new boss premium, difficult company premium, ghetto location premium (yes, I am serious), or discounts for that matter
Always set a target for what you consider a reasonable increase in addition to the above. This includes any additional external education and also building of knowledge in your current job.
Using this methodology, in the past 4 years, I have gotten these raises...
Internal...15%
Internal 20%
Internal 10%
External 75%