Do not point out the injustice, this will really piss people off and quickly. Also do not point that others get paid more than you, again pisses people off.
If you want a rise, you have to be confident you're good at your job (and actually be good at it), make sure you can demonstrate the value you bring to the business. What I mean by this is have some clear examples of where you have gone above and beyond what your job normally requires of you, if anyone has ever given you positive feedback such as a customer or colleague then mention that.
My 2p. Best of luck with the appraisal.
If you want a rise, you have to be confident you're good at your job (and actually be good at it), make sure you can demonstrate the value you bring to the business. What I mean by this is have some clear examples of where you have gone above and beyond what your job normally requires of you, if anyone has ever given you positive feedback such as a customer or colleague then mention that.
My 2p. Best of luck with the appraisal.