Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
This sorta depends on what type of smoker we're talking about...most manufacturers will include some directions in the owner's manual about how they suggest seasoning/prepping before cooking in it. If no instructions are included, the first thing I'd do is run it really hot - the hotter the better - for at least 2 hours completely empty. This should burn off any manufacturing crud/oil/grease that's left in there from the factory. After it cools, you may need to take some rags and some warm soapy water to wipe out the the ash/residue from the burnout. Then you can put a light coat of cooking oil (cooking spray works, or any vegetable oil) on all chamber surfaces and start cooking.