When you are planning for a salary hike, you should have proper Performance Appraisal System in place. After arriving at rating scale of individuals you can arrive at increment slab. Increment slab is something based on your Management budget for increment for this financial year. Say overall 10 % -11% or 15 % company vide or it may more than that based on performance of the Company volume of business /sales target achieved.
Immediate Supervisor of the employee has to evaluate the performance of the employee, need to have one to one session, employee should be briefed about his strength and weakness, where he /she need to improve.