I cooked chips (thicker than french fries) for the first time yesterday and they were gorgeous! This is what I did:
Preheat oven to 250C for 6 minutes
Slice potatoes into chips
Spread out evenly in a 9" non-stick baking pan
Toss with a small amount of virgin olive oil (you can omit this but makes them crisper)
Reduce oven heat to 200 and put pan on high rack
Cook for 10 minutes, turn them over then reduce temperature to 180 and cook 5 minutes more. Perfect!!