Here's what you are going to do. You are going to smoke your turkey to an internal temperature of 165 degrees F. This means that the coldest part of the turkey is 165 degrees F. This isn't a suggestion. Test in at least two places (or more) and remember that turkey bones heat faster so keep the thermometer away from bone. Also, dark meat should be cooked to a higher temperature so worry about the breast, but make sure to check the thighs as well.
Run the smoker at temperature range of 235 degrees F to 250 degrees F. Plan on 30 to 40 minutes per pound.
What you need to smoke a turkey:
The first thing you will need for a good smoked turkey is a good turkey. Now, whether you are going to hunt your own or buy one, make sure it is a fresh turkey. This means an all natural turkey without injections and solutions. I know this isn't always cheap or easy, but if you can get one, then I recommend it. If you do pick up a frozen turkey, always follow the instructions for defrosting. Also do not get too large of a turkey. A 20 pound turkey will take 10-14 hours and larger turkeys greatly increase food contamination risks. A 12-16 pound turkey will be good and if you need more, try smoking two turkeys.
You will need a smoker, a good meat thermometer, a good hardwood like cherry or apple, and some patience. For the smoker you can use a kettle style grill if you are familiar with low temperature cooking in it. Most people don't cook turkeys very often, so even if you are a master of smoked brisket or low n' slow barbecue ribs, you should pay particular attention to what you are doing. Nothing can take the place of experience.
The good meat thermometer is a must. It should read fast and be very reliable. For the wood, I recommend a fruit wood because the flavor works best with turkey. Something like a cherry or apple would be good, though hickory and oak can add a nice flavor as well. Be careful not to over smoke a turkey, especially if you are doing a long smoke.
Smoked turkey has a different color and texture than oven roasted turkey. The meat may appear pink and have a smoother texture. This is normal. The smoking process causes a chemical change in turkey that changes the color of the flesh. As long as the turkey registers a temperature of 165 degrees F. it is safe to eat no matter the color.
Want to see this in more detail? Try Smoking Turkey - Step by Step.