Dear Pavan Ji,
You need to devise the Incentive structure basis the company goals you have set for the year. Company goals can be further broken down to set departmental or individual/role goals.
I suggest you learn & use the MBO (Management by Objective) system. MBO system uses quantified goals to calculate the performance linked incentive payout. Each and every objective is range bound with a weightage. You can keep a 30:70 ratio for company goals to role goals. Company goals could be measured in EBIDTA, Customer Satisfaction index, Cash Flow, order book value etc. Role goals for sales staff could be Net sales, credit days etc. Role goals for Marketing should be related to goals assigned to sales employees, and few examples include number of campaigns, product development, net sales, cost of pop material etc.
That's all i can suggest. Hope it helps.
Regards
Rahul Chhabra