I generally wear just a T-shirt and shorts but like the others have said, whatever you feel comfortable in will be fine.
I tend to eat Bananas, porridge, that sort of thing a couple of hours before I go (depends on how long I am running for), when I started running it was lack of liquid in me that I really struggled, make sure you are nicely hydrated before hand and take some with you.
As for running style, I'm still concious that I look like a 'plodder' but over time I've become a quicker plodder than I was at the beginning.
Correct footwear very important.