Use byadagi red chilli, it's mild, tasty and gives good colour to your dish.
Byadagi is the name of a place in North karnataka, as this chillies are grown in this area......so byadagi chilli. You'll get in super markets, more....big bazaar. .etc.,
You can also add coconut milk. The coconut milk helps to keep the thick and creamy consistency of the curry. Also you can use Kashmiri mirch powder or degi mirch to add color to the curry and do not have soice. Paprika or Cayenne are the red chilly powder that are very spicy. If you like less heat in spice and the recipe calls for red chilly powder, try using in the ratio 1/2 tsp degi mirch or Kashmiri chilly powder and a pinch or 1/4 tsp cayenne or paprika.