Keeping sales compensation simple (How the variable part is calculated) and generous will ensure that your sales team is motivated and wants to make deals happen. Ideally, a salesperson should be able to calculate her commissions in her head or on the back of an envelope; you may find that your CFO or CEO wants to put a super cool, and complicated formula in place for calculating incentive comp and you should resist this. Nothing discourages a sales team more than a commission system that is complicated and opaque. Or one that squeezes them.
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