Quoted:
1 mile = 7:30
3 miles = 8:30
6 miles = 9
9 miles = 9:30
12 miles = 10
13+ miles = 10:30ish
I'm allegedly running a marathon (26.2) in 2 months and i have a feeling I'll end up around 11 minutes per mile there. However, I signed up for a pace group that will run 10:30s so we'll see.
I tend to start out slower and and settle into a good pace. I really try for negative splits (run second half faster than the first). If I have anything left in the tank, I sprint the last quarter mile.
Sometimes I'm just tired or not feeling it that day and if so, I'll plod along at a slow pace (maybe 10 min/mile) for only 2-3 miles and call it good. I figure it's 2-3 more miles than most people got in. OTOH, sometimes I'm just feeling good and everything is falling in line and I'll smoke out long distances at faster paces.
It's supposed to be fun so there's no sense in killing yourself if you're not having a good day.
My generic advice to running newbies is to run for time, not pace or distance. In other words, run 30 minutes instead of 3 miles or 10 minute miles. Just however long you happen to run in 30 minutes. You'll figure out what a good pace for you is soon.
Absolutely everything he said, with the exception that I usually run for distance, not time. If I only have 30 min, then sure, I tune my workout to that. But ideally, I shoot for distance, and it takes as long as it takes. And yeah, emphasis on the fact that if it's just not an "on" day, don't kill yourself over it. Do what you can so you're still getting a workout, but not injuring yourself, or making yourself hate it so bad you stop.