I started running about 7 or 8 months ago to get in shape and lose weight.
Started out just trying to work my way up to a mile, which eventually became 2 miles, which became 3. After a half a year, I now run about 3 1/4 straight every other night, including a half mile walk to and from the course. My best time so far has been around 27 minutes for a measured 3.1 mile run. So, I entered a race for next weekend...a 5K (3.1M)

I know I can finish with no problem, and I know that I wont be competitive (because last years top ten ranged from 13:40 - 15:00)...but still, I want to do my best, and train smart for my last week.

What can the experienced runners here tell me?

My goal is to do this, and work up to a 10K by spring...and then hopefully a half marathon by next fall.

get a quality pair of shoes. train on hills. control your breathing, find a rhythm. and remember the story about the tortoise and the hare.

Find someone in the race that appears to be in your class, and pace yourself with them. You'll both do better for it.

Trust me,  just competing against the other runners will shave a couple minutes off your time.

Trim your toenails BEFORE the race. Drink a lot for breakfast, no alcohol though. Piss before the race, not during! Wear almost new socks. Finish first!

Good luck.

And shave all your body hair to reduce drag.  You'll pick up a couple minutes, trust me!  

If you want to get good at it you have to run long slow distance in practice.  I used to run 6-10 miles a day.  Sometimes 4 in the morning also.  My time cross country (over the hills and through the woods) around 15:30.