My twin boys are 14 months now. We do a lot of finger food and they're really good at feeding themselves with their hands. I'm completely stuck at how to teach then to spoon-feed themselves. They like sloppier foods like shepherd's pie, risotto, porridge etc but they get fed up of me spoon-feeding them after a few mouthfuls. They manage quite well to feed themselves if I give them a loaded spoon but if I give them a spoon to dip in the bowl themselves they just look really confused.
She has been feeding herself a loaded spoon since about 9mths and in the past few months has been attempting to spoon things herself.
Like you say the sloppier foods are the best times to try. We have always made a point of scooping up her food in front of her and eating as a family so im guessing thats helped model what to do. She is now pretty good at using a spoon herself with a yoghurt and getting there with other foods.
Sometimes a fork is easier as it stays on the fork better once its been stabbed. Although it can be painful watching dd trying to stab something over and over again. She finally gets frustrated and just picks it up!