Many individual pay reviews take into account individual performance, which may be assessed through an appraisal scheme. If you are going to be asked to participate in an appraisal process, it is a good idea to be clear early on about what skills you are being assessed on.
Once you know this, you will probably find it helpful to record (throughout the year) specific examples of how you've met the required criteria. If at appraisal time, you can refer to particular instances of how you've fulfilled the criteria, it will be harder for your employer to mark you down on contested categories.
Also, if you feel that your employer's scoring is discriminatory, or unfair for some other reason, having this information ready to hand will help you in any grievance or tribunal claim you might bring.
Many unions have put helpful guidance and checklists on their websites which you can use to help you prepare to get the best out of your pay and performance review. It is well worth taking a look.