Had the same problem. Two things that worked for me:
1. Get a weed hound or hog i forget the exact name. Take out as many as you can now and before they release seed. I did that for 4000 sq feet one spring. Hard work but great as it takes out the tap root and aerates the lawn and its kinda satisfying after a crappy day at work.

2. Weed b gon max. It works. Every weekend i would go out and spray any dandelions i saw (the ones i couldnt be bothered to take out using the weed hound), it takes a few weeks to work but keep at it and go back and respray every week. It kills it from the root. I kept mowing over the yellow flowers b4 they turned to seed and im guessing that helped as well.

I did both of those one spring, and by the following spring you could count the number of dandelions i had on two hands. This year i have a few but i use the weed hound when im feeling fit and i spot spray every week until they die as well. Now under control

With regards to the seeding. Im unfamiliar with the scotts steps, but i bought some pennington smart seed and threw it down in the fall after i killed off all the weeds in spring and it grew great by winter. Now i just fertilize every 6 weeks with scotts turfbuilder BUT never in summer and everything looks good.

Good luck, im sure the experts here will give you some more detailed advice!

I have used Scott's 4 step program on my Iowa lawn in the past and found it to be good for Scott's bank account and bad for my lawn.

I now only fertilize twice in the fall with the Scott's "Lawn Pro" brand fertilizer.

I mow at 3.5 inches and spot spray all weeds with TRIMEC when I see them.

I also have a weed-hound and use it mainly on Black Medic.

If I were you ... I'd raise the blade on my mower to at least 3 or more inches. Stop fertilizing until September. Spray your entire yard NOW with a hose end sprayer of Weed-Be-Gone per the instruction on the container.

Respray the yard again in mid Sept.

Digging lots of dandelion now with a weed hound will just make lots of holes in your lawn. But, it might help you feel better. but you will notice the holes and the mowing will be bumpy.

Plan on at least 3 seasons to get on top of a dandelion crop. Then you can post again on how to kill the creeping charlie that's probably in your lawn (grin) Hint: TRICLOPYR

Dandelions will invade thin lawns or lawns that are mowed too low for their type. Some lawns do better (more dense) when mowed low but those lawns are not popular in Chicago. Raise your mower to at least 3 inches. Also if you have a fescue lawn, plan to reseed at the end of summer (every summer). That will improve your grass density.

I get them with the weed hound the day after it rains - I do not feel like the yard gets bumpy. I make the rounds every couple of days and get a small bucket worth.