Analysing where the pain is in your current operation is usually the best starting point for any new software purchase.
How much is worth automating? What can you do already to handle the amount of orders you currently have.
How well are you coping in the peak periods? Do your warehouse staff dread Black Friday?
The risk of operating with the all seeing and all knowing warehouse manager is a problem which creeps up on you.
Is the inventory on your website up to date? Are you finding your selling stock you don't have?
How efficient is your current setup? Have you squeezed as much as you can out of your current setup?