Step 1: The Quote
Know your specs. Size, page count, and quantity. Ordering 100 books costs much less per unit than ordering 1.
Step 2: The Proof
Always order a physical proof. seeing one copy allows you to catch typos and color issues before you commit to 500 copies.
Step 3: Distribution
Consider how you will ship. If you are fulfilling yourself, do you have space? If not, look into fulfillment services.