Although chip lights are not generally of themselves emergencies (engine chips are an exception) always follow the flight manual, which governs what the experts believe.
Having written a fair share of emergency procedures, generally land as soon as practicle means an airport/heliport, "Possible" means a golf course or similar, and "immediately" means IMMEDIATELY (not necessarily ditch if the sea state and temp are of themselves life threatening.
Declaring an emergency is a good thing for most deviations from the norm. It is not admitting that you are chicken, it clears the mind of controllers and the like, who sometimes place helicopters near whaledung priority-wise, and it explains to folks what is happening as things sometimes turn to worms. I have investigated too many accidents where a declaration would have made the difference between surviving and not.
Of course, if you declare for a hangnail, or some such truck, you buy in the bar on the hill near Stratford!