When you have a Sim in the toddler stage, it's easy to put them into platinum mode. And you want to do this, because the math on their lifetime aspiration score is far more favorable than it is for adult Sims. This means that a few simple actions can quickly boost your toddler Sim's lifetime aspiration and get them a great head start in life.

The "big three" are Potty Training, Learn to Walk, and Learn to Talk. Obviously, your toddler will need the assistance of an adult for these. To potty train your toddler, you will need to switch to Buy mode and purchase a toddler potty chair. Then switch over to an adult Sim, click on the potty chair, and choose "Potty train _____." To teach a toddler how to walk or talk, while you are controlling an adult Sim, click on the Toddler and choose "Teach ____ how to walk" or "Teach _____ how to talk."

In order to decide which of the big three to work on at any given moment, I switch over to the toddler Sim. At any given time, a toddler Sim is likely to have one of the big three in their Wants panel. Right click on that Want to lock it (just in case) before switching back to your adult Sim to start the training.

Toddler training can be sped up by feeding your toddler Smart Milk. The Smart Milk machine is an aspiration reward which can be found in an adult Sim's Aspiration Rewards panel. When your Sim is in aspiration gold level or above, feed a bottle of Smart Milk to your toddler. The toddler will be surrounded by an ethereal glow, and will learn their skills far faster.

There are two down sides to Smart Milk: first, your adult Sim needs to be in gold aspiration or above. This can be tricky, particularly for a Sim who has been working as a parent. If your Sim is in green or red Aspiration when you prepare the Smart Milk, your toddler will lose a skill point. (Normally the bottle will glow green. If it glows red, it's bad milk. Dispose of it before feeding it to your toddler.) Honestly, the Smart Milk is such a pain, I don't bother.

When you teach your toddler to walk, they become significantly more mobile. Walking toddlers will go outside (theoretically crawling toddlers could as well, but I've never personally seen it). This could be dangerous because they don't change into outdoor gear before they do so.

After your toddler learns to talk, they can carry on "conversations" with older Sims. These conversations consist of talking bubbles with pictures inside. Much as with real life toddlers, conversation with a toddler does not seem to be particularly gripping for adult Sims. It's cute, though.

Potty training your toddler is handy, because once they are potty trained, they will help themselves to the toddler potty. (Your adult Sims will still need to empty the potty, of course.) However, potty training takes several sessions.