ADVENTURES IN PONYVILLE
Tips /co/ has figured out.
The minigames have two purposes: points and sparkles. Sparkles help towards getting your cutie mark, points unlock more dress-up options for your pony. If you want to get the cutie mark as fast as possible, you will get more sparkles by purposefully losing the games early on and starting them over and over again. Play higher difficulties if you can: they give you more point for dress-up, and you lose them faster for sparkles.
DASH'S CLOUD GAME
An easy source for Generosity and Loyalty sparkles. Just save your partner a few times. Rain clouds are no big deal as long as you have some sort of downward momentum. Higher difficulties mean more rain clouds.
PINKIE'S CANDY GAME
A terrible source for points, but a fast way to get Laughter sparkles. Don't worry about the boxes, just keep clicking one of the dishes and dropping the food. Pinkie will come out to refill it. Feed Pinkie candy a few times to get the sparkles. Higher difficulties mean a faster belt.
APPLEJACK'S HARVESTING GAME
A good source of Honesty sparkles. It's a poor source for Kindness, but it's also the only reliable source for Kindness. Kindness is a bitch. If you run Applejack's retard cousins off about 5 or 6 times, you'll get 4 Kindness sparkles. That's the max you can get, so if you're grinding Kindness you'll restart this one a lot. Baskets of apples can be planted to make new trees with the same color apples you planted them with. Use this to get more red apples and avoid greens. Higher difficulties mean apples decay faster.