Years ago, I used to work in advertising as a creative director. Part of my job was hiring models for a local deptartment store's ads and catalogs. Therefore, I have a lot of experience working w/models.
And, more recently, DS was called to model 2x for Fisher Price toy boxes.
Let me start by saying that if you're dealing on a local level, you do not need an agent. You can be a "freelancer". You're probably thinking "sure, but how do I make the contacts?" Depends on your area. I mean, if you're in NYC, I'd say get a modeling agent (and a good one). However, if you're in a small town or city, do it yourself. You can create your own headshot card ... front has a close-up of your child. Behind the card, you'd put 3 photos of your child "modeling". You can use casual shots that you've taken. Include recent photos ... nothing too old b/c if she's not a baby, nobody will care what she looked like as a baby. Remember to include all vital stats -- child's name, eye color, hair color, height, weight, clothing size, phone number, parents names, child's age.
Next, do some research. Find out who your local advertising agencies do business with and if any of them use models. For example, if you have a local department store that advertises (not a chain), their ad agency will hire the models for the photo shoots. Call the local advertising agencies and ask if they hire models. Most do. Then, ask who would you send photos for consideration to. Get as many ad agency names and send your photos. Ad agencies keep those photos in a file based on child's age. Keep updating photos every year w/that agency. If they need a child in a certain age range, they'll pull their file folder and go through it. If they like your child, your child will be called in for a "go-see" -- where basically, the creative directors want to see what the model looks like in person, if they're sociable, if they follow directions, etc. Often, we'll take a photo of your child for the files. Going on a go-see doesn't mean you get the job. It's just that -- a go see if we like your looks.
What's nice about freelancing is that you do not have to pay a percentage of your earnings to the agency. For example, if I booked your child, at the time I worked, they'd get $50 for their appearance for catalog (which was basically 1 hour b/c that's the limit for children). Parents got $50 clean and clear. Now, if I paid a modeling agency, not only would I have to pay a booking fee, but they'd take a percentage of your money for their profit.
The work for getting your child's photo out there is a lot in the beginning ... getting the head shots, sending them out, making contacts, etc. If you work w/an agent, then that becomes their responsibility -- but w/that comes $$ out of your pocket. Regardless, whether you do it yourself or go through an agency, there are no guarantees.
As far as DS getting called for Fisher Price toy boxes, we live near East Aurora, where Fisher Price is located. Every summer, they have "Toy Fest". At toy fest, they do an open call for potential models. They have the kids sit in one of the Power Wheels trucks, they put their name on the Power Wheels windshield and take their photo. From the thousands of photos they get from that, plus all the others they get from local modeling agencies, they select kids for boxes or to toy test. DS was called in twice for boxes. We did not pursue this whatsoever. He wanted to sit on the powerwheels (w/o realizing it was for potential modeling consideration) and we let him. We didn't even give a thought to being called for modeling! It just wasn't something we were pursuing. We let him do it and tucked the money into his savings account.
Also, not to discourage you ... but many local small companies, like the furniture store the OP mentioned, will call in friends and relatives to do these ads as opposed to using models (which costs $$). I've had some small companies for clients and they'd use their own "talent".
Finally, there's nothing worse than a stage mom. Once, when we were casting a commercial, I happened to be walking to the conference room where we had the casting call (I was one of the people making the casting decisions) and heard a mom threatening her child that if he didn't get the commercial, she wasn't going to do this anymore. Well, let me tell you ... when they came in, I told the woman what I heard her say and that if her kid didn't get the part (which he didn't), it wasn't b/c he wasn't good enough ... it was b/c he didn't have the look we were after.
Now, the beauty pageants ....... don't even get me started on those!!!!
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We want her to stay a little girl for as long as possible. And in these times, its not long. 
