Explore Often
When going through the game, it's important to gather essences as you go. Essences can come from all manner of places. For instance, fishing in a lake can come up with the essence of tires, electric eels or crabs. Gain essences by shaking the fruit off trees, chopping down trees for wood and prospecting and digging up essences from the ground. Essences are then used to paint interesting patterns on furniture for decoration, increasing neighboring characters' happiness through the game.
Since the world in MySims is so large, and will get larger as you progress through the game, it can take extra time to find all of the necessary essences. Because you will need them when you paint furniture for your neighbors, it's important to collect as many as possible. After every house built or furniture given to a neighbor, go around the world collecting essences. You may also find new areas in which to explore. By exploring often, you will regularly have the right number of essences as soon as a new neighbor makes a building or furniture request.
Pay Attention to the Sims' Personalities
MySims is all about pleasing your neighbors. Each character has her own unique personality. For instance, Poppy loves cute and fun things, while her sister Violet loves spooky things. Essences come in six categories: cute, fun, tasty, geeky, studious and spooky. When building a home for a Sim, make sure to have the building reflect that Sim's style. For example, add garden gnomes to a home's exterior for Sims who like fun, and add pig statues for those who like tasty elements.
Personalities also apply to what goes on inside the Sim's home. Decorations are very important. When a character asks you to build him a table, create something that he will genuinely like. Violet, the lover of spooky things, probably wouldn't like a table covered in smiley faces. By focusing on their likes and dislikes, you will fulfill each character's request and make them all happier in the process.