If you are an accomplished enough diver to go off on your own with a buddy and dive, it is important for you to use a dive flag.
Talk to each other. Learn about each other’s experience level and last dive.
If you see another diver looking at something or pointing or taking a photo and you are curious, then approach slowly.
Welcomed help is a wonderful thing, but nothing is more annoying or potentially dangerous than having someone try and help without being asked.