Know Before you Build

A few things I've learned along the way...

If possible, build the mansions for your Sims, they come pre-furnished with three star appliances, furniture and a three star CAR! And an extra large lot to add onto!

These houses do cost extra, but they only cost Simoleons, not LPs (and it would cost a lot to get everything the house already comes with)

Also, after you build the Car Yard, get the red Sedan, your Weekly Challenge will require it and that way you already have it.

Make sure that all your Sims are gardening, baking or at work at all times, the farther into the game you get the more expensive everything is and the last you want to do is get caught without enough money and have a timed Quest on your hands!
Things like Peppers bring in the most money, they're free and if you have 10 Sims growing them all at one time you can make $80 every minute. That's $400 every 5 minutes! Or $1,000 every 12.5 minutes!

If you have babies, have them sleep all the time. When they wake up you will get some 200+ XP without raising a finger and they're out of the way. Just make sure all their needs are met in the in-between time.

Pets are great at finding money, the higher the rating the more they'll find. I've gotten LPs from 1 star dogs and cats before though, so don't put it past them. And Rabbits cost money, not LPs, making them a good choice if you're trying to save up.

Make sure to check the Shopping Cart often for deals to get free LPs (your best bet are the videos since they're guaranteed free and they don't require any personal data). In the Upper Left Hand Corner is a blue diamond, that's where you access the free offers.

The more your town is worth the more LPs you can earn from it.
Also, leveling up is another great way to earn LPs.

If you have any suggestions please comment below, I'm sure we all would like to know.  

Toddlers Quest (Part 1)

This task looks like one of the hardest ones to accomplish in time. We shall see...

You get 4.5 days.

First, you need to watch a documentary, then a kids show, both on the T.V. and change your baby's diaper.
Here's where it gets hard. You have to build the Pet Shop, which cost $100,000 and takes 36 hours to complete construction. (I thought the bridge was bad!) It took me some 7 hours to get enough money to build it. However, I would save your LPs until you absolutely need to use them.
I like to wait until construction is down to 1h 59 min. to use a LP (you cut construction down two hours and only use one LP)

My pet shop still has about 30 hours on it.

One of the best and fastest ways to earn money is to get a garden patch for each of your Sims and place them all at one house, gather all the Sims at that house and garden. If you're going to be sleeping or unable to connect to the internet I suggest Onions or Beans. Otherwise have half do Peppers and the other half Carrots. I was able to make $4,000 in under an hour with 6 (or so) Sims. Also, remember that you can make $300 every hour just by checking your 'Starter House' every minute. Plus, your dog can't hurt.