Having a cat can actually help: toddlers can imitate the cat and it raises their Imagination skill. Talking to it raises Social need and Communication skill.
Seconding the priority on Potty Training - once they can go by themselves, you're so much better off as their hygiene usually doesn't drop all that fast.
Have them Walk Around or Run Around to raise their Motor Skill, especially if you have stairs in the house. Dancing also helps. If you have a Charmer toddler, they're going to need more attention: Read To Sleep is a nice combo of raising Social and Fun for both the toddler and the adult Sim (and Imagination for the toddler).
Naps in the middle of the day are good: have the toddler take one when their Energy is dropping to orange to tide them over until nighttime. And it'll give your adult Sim time for other stuff.
Another +1 on the meals: they can Grab a Serving from any surface and feed themselves. The toddler meals you can give them in the high chair aren't as filling as proper full meals. If you want to keep using the highchair, go with "Pick a Serving for..." from a group serving option. Definitely suggest making the Family or Party size options as they can go a long way both for the adult Sims and for toddlers, rather than making single servings.
Hope that helps.