At Exterior Walkways
Your high traffic areas should be well lit at night to avoid tripping hazards. Solar lights that line a pathway, in stairway lighting, or small floodlights that illuminate entry ways are a great way to keep those entering your home safe (or make sneaking up to your dark home more difficult!)
Inside the Home
Two of the biggest mistakes homeowners make with indoor safety lighting when they are away is 1. not lighting the home at all, and 2. Putting a few lights on permanently. Each of those options are a clear indication to intruders that you are in fact not home. On the one side, leaving your home dark, not only signals that you aren't home, but makes it really easy for intruders to come and go unnoticed. And on the other side, leaving lights on continuously can make your home look awkward and stick out like a sore thumb when, say, your porch light is on in the middle of the day, or your bedroom light is on at 2AM. Indoor lighting on timers is your best option. Choose a few key locations and time the lights to come on and off and natural times. Have them come on as the sun sets, but turn out by 10PM or so.
Near Windows and Doors
Every homeowner should have outdoor motion detection lights near doors and windows. Don't let possible intruders poke around undetected and allow them to discover entries to your home that are completely hidden by the cover of night. Instead, place a few motion detection lights in key areas of your home that will be triggered as necessary. And hey, a sensor light is also really handy (and hands free) for those nights taking out the garbage!
Illuminating the Yard
Floodlights to light your yard, especially if it's a large one, are a really good idea. Just as you want to keep doors and windows lighted, you want to keep the yard and its possible hiding spots in the light too. You don't have to obnoxiously fill the yard with daylight, but don't give passersby a place to lurk.