First of all, what type of grass are you growing? For northern parts of zone 7, you would be growing a tall fescue mix. For those, generally, it is best to do lawn repair in the Fall, as they are cool season grasses and the weather remains cooler for longer and it rains. Next best time is Spring, and given the late and cool Spring, now would be a good time to start.

If you are growing warm season grasses like bermuda or zoysia, they are not actively growing yet. One of them is grown from plugs rather than seeds, I forget which. I don't grow this type.

I would work on the front-yard first because it sounds like less work, and you can gain some experience. This is if you can wait.

Regardless, first step would be to apply a broad spectrum weed killer. Preferably that kills both broadleaf and grassy type weeds. Wait two weeks after application. Let the chemical work on the weeds Then get a manual lawn aerator, if you lawn in small enough. I have Yard Butler. Get two prong one, less strength required to push in. Available from amazon and big box stores. You push it into the soil by stepping on it with your foot, and two plugs of soil will come out. Don't get spike aerators. They just poke holes. Does not help with compaction.
Spray the holes with WD-40 before use. Water the soil well before use. It should not be soggy, but soft enough so you can push the thing in. You will need to unclog the holes periodically with sticky clay soil. Reapply oil spray after unclogging. Keep something handy for poking. I used a metal barbecue skewer.
Next spread a thin layer of compost, maybe 1/4 inch to 1/2 inch. Compost and core aeration will help loosen your hard clay soil, and help grass roots penetrate.
You may need to apply lime as well if your soil is too acidic. Grass likes more neutral soil. If you have moss growing that's a clue it is too acidic. There are soil text kits for checking ph.
Bulk compost delivered by truck is generally cheaper for large quantities, but advantage of bagged is you can take your time, and not have to clear out that big pile on your driveway before it rains or you have guests, etc.
After that you are ready to spread seed or sow plugs. You do not use regular fertilizer when you seed. It could burn the new seedlings. You could skip it, and apply after 6 weeks once the new grass has come in and is 4 inches tall. Or you can apply a specially formulated starter fertilizer.
If you seeding, you need to keep the soil surface moist until the seeds germinate. You don't need deep watering. Just frequent shallow watering just enough to keep the surface moist. As grass starts growing you will gradually switch to fewer but deeper(longer) watering.

If you are sowing seed, you will keep over-seeding every fall until you get grass growing thick enough to suppress weeds.

I looked at broad spectrum weed killers last yr but was not really impressed by any. Is there a certain brand that you would recommend?

I've used Ortho products from home depot. The chemicals available directly to consumers are not as strong as the ones pros use, and if too strong, it could harm the grass. So don't expect all weeds to be gone with 1 application, but it should help reduce their numbers.

I'm real hesitant to get involved with this, but if I do I need to know where you live. Zone 7 covers the world including just about every climate and soil situation. Need a town and state.

The reason I'm hesitating is you are getting the worst advice possible from somewhere. Since you had to dethatch I assume there was originally grass there. What kind was it? Most grass does not need to be dethatched, and some kinds will completely die from dethatching. What seed did you put down?

Your jar test gave you 50% clay? I suppose that is possible. How many brick factories are there within 50 miles of you? If you have none, then your jar test was done wrong and gave you the wrong idea about your soil. Almost nobody has any clay to even mention. 50% would be a rarity. So you put 6 inches of soil in the jar, washed it around with water, and 2 days later you only measured 3 inches of sediment? That would be what you'd see with 50% clay.

Your watering regimen was wrong for new seed. First of all the seed needs to be in contact with the soil. Did you have bare soil to seed or were you seeding through existing grass? If the seed was not touching soil, it might germinate but it won't take root. New seed should be watered 3x per day for only 5-10 minutes to keep the seed moist all the time. It should not be allowed to dry out for 1 week (rye seed), 2 weeks (fescue), or 3 weeks (Kentucky bluegrass). If you used bermuda then a myriad of other mistakes were made, but it doesn't sound like you're in the south. Once the grass is up, then you should back off on watering. By the time winter hit you should have only been watering once per month, not once per day.

Milorganite is a fine fertilizer. I don't use it but I know many lawn gurus who swear by it.

I would not worry about weeds until you have grass. If you use the wrong herbicide you can hamper your efforts at getting the grass established.

As for your back yard, it sounds like you have the wrong dog or the wrong attitude about what dogs do. We got a Catahoula leopard puppy last summer, and my entire back yard is his to wreck. We only wish we had a larger yard for him. He's a dog and wrecking stuff is what they do for at least 2 years. Now that he's full grown we're taking him to an open space dog park to play hard with other dogs. Having a tired dog has taken some strain off the lawn, but if he left today there are parts which will not recover for at least a year. He just loves that swing hanging from the tree! If you want to do something to help both of you, consider bringing in a couple inches of chipped tree trimmings as a mulch. Dogs love it and it will actually improve your soil underneath over the years. Then when the dog slows down, you can rake up the mulch and start your lawn again. That's our plan anyway.

If you decide you want grass there, do not till. Tilling is another piece of horrible advice about lawn preparation. I'm not sure who started it but the reputable publications all say not to till. There is only one way to rototill properly and unless you have a tractor, you can't do it.

I guess I got over my hesitation to get involved, but if depending on your answers to the questions, there is a LOT more to say. You also need to unlearn a lot of what you already know about lawn care, because 1) it isn't working for you, and 2) it's not right...which is why it's not working for you.

Hey dchall,

Thanks for all the info. First off, I live in South Jersey (Cherry Hill to be exact). The reason behind my concern with the clay in my soil is because part of the area where I wanted to do some landscaping has many characteristics of clay soil. I think it is a result of the fact that a brick patio was originally there for x number of years. From the test I am assuming that the soil is mostly clay but I could be wrong because I am a newbie at all this :).

The grass I tried to grow last year was Northern Fescue. It took root in some areas but not in all. When looking over my soil I noticed that it is very compact all over. Not to mention there was years of grass clippings all over the lawn. This is the reason I dethatched my lawn in the hopes of getting soil contact when seeding.

Right now my lawn has a few weeds starting to grow. I am not sure if they are just left over dead or new growth. I have been debating from your post now whether to put down a weed killer or not. Would you recommend I just seed wait 4wks then fertilize while also following your watering scheme?

Yes I would do that. Then in late May see if you might want to spot spray the weeds.

If you have a lot of old grass clippings, your soil is not healthy. I would start fertilizing with organic fertilizer. Once per year should be enough, but you might want to go a little more frequently go kick start the process. My favorite organic fertilizer has been alfalfa pellets (rabbit chow) for the past couple of years when the price of corn was high. Corn has come back down now but not all that low compared to alfalfa pellets. The application rate is 20 pounds per 1,000 square feet. You can apply any time of year. You can apply it before, during, or after you seed.