Hi, I love running- haven't done it since it got cold though! My suggestions are:
1.Go slow - don't worry so much about how many calories your burning, etc in the beginning- you will be burning lots since you're new to running anyway
2.Walk for awhile first to warm up- especially if it's cold. Do some stretches, then jog slowly until you feel winded, then walk, jog, ....
3.Make sure to breathe and don't push yourself too hard or you'll get side stiches and have to stop anyway. I wouldn't run any hills yet either- they're tough! And don't run down hills (bad for joints).
4.After your cool-down walk, stretch well!
5.Expect to be sore! I'm always sore once I get back into running after a break, even though I stretch.
6.Even if it's cold out, don't put on TOO many layers because you'll get hot fast. (I'm not saying to run in shorts and a tee though!)
7.And remember, just go slowly- it's a great cardio workout (great leg toner too) but can be tough, even after you've ran for awhile.
GOOD LUCK!