If I am going any distance I carry a minimum of;

tools and tyre levers
spare tube
pump
water
cel phone

Unless I am certain the weather will remain nice I also carry lightweight rain / bad weather gear.

The Planet Bike Superflash is probably the best rear light out there and these are fairly inexpensive... front lights are more expensive when you want illumination and not just lights to help you be seen.

3watt lights are a minimim for this, I like my 10 watt Nighthawk as it turns night into day.

Mounting a rear light on your helmet is one of the cheapest and most effective ways of being seen from the rear and the benefit is that it is always with you.

My winter helmet has front and rear lights.