1.  What needs are being met by the product purchase? What are the benefits to the consumers? Make sure that you differentiate between features and benefits; go beyond manifest motives and consider latent motives.
2.  Who is involved in the purchase process? Who are the influencers? Who are the buyers? Who are the end users?
3.  Where are the products sold, and what are the distribution channels?
4.  How often are the products purchased? Is there seasonality to sales?