Here's what I do to my auger before I go out, and I have had the same auger for 10 years now without a problem.
1. Install a new plug new plug, and buy a spare and make sure you have a sparplug wrench with you. When you buy a new plug I would stay with the recommended plug for your particular engine. A parts store can look that up for you if you're not sure.
2. Drain the gas tank and rinse out any crud and water/ice from it. It's easy enough with an auger to just tip it upside down for this and catch the gas in a coffee can.
3. Unscrew the float bowl underneath the carb and rinse/blow it out. Be careful when you do this that you don't lose the needle valve, but if you don't mess with the float itself the needle valve should stay in place.
4. Remove the breather cover over the carb and wipe/blow the front of the carb with compressed air.
You didn't say what kind of an auger you have but if you see a small foam air filter (usually green) you should either replace it, or rinse it out well with gasoline and let it dry before putting it in.
5. Fill it up with fresh gas, and you should be good to go on the engine.
6. Look for a filler plug on the gearbox, of you have one, remove it and stick your finger in the hole. You should feel lubricant. If you can't you should add some gear oil, but don't overfill it... just high enough that you can reach it with your finger is fine.
7. Last check your cutting blade for bent sections and take care of those. If it's got lots of dings and nicks you may need to use a file and dress it up slightly but go easy on it so you don't mess up the blade angle. Try to stay with the original blade angle on any filing you do.
If any of this makes you squeamish, then I would definitely take it to a professional!
One of the other things I feel I should mention is that it's a good practice to warm up your engine before you start cutting. I've seen guys crank up a cold engine and start right in. IMHO, you should always warm it up before you put a load on it.
