First question: Where do you live? That makes a big difference as to the advice we might give you. And as a corollary to that statement, not knowing where you live is why there are no really good lawn books for you. It seems to me that the lawn books are all written in Indiana for Indianans. So if you live in Minnesota, Vermont, Florida, Texas, Washington, or really anywhere outside of Indiana, the advice will not be the best. And if you live in a big place, please tell us what town you live in. For example SoCal has every hort zone and soil type, so just saying SoCal is not helpful. Even saying Los Angeles is not good because there are not that many lawns in LA proper. Plus LA extends from Long Beach to Santa Monica which covers a lot of ground.

What kind of grass do you have and what do you want to have? Do you just want it green, do you want it to be all one type of grass, or do you want it to be the nicest lawn on the block?

Lawns need water, mowing, and fertilizer. If you are doing those things right, then they should not need dethatching, crabgrass control, other weed control, insect control, or mechanical aeration. Lime is a different topic. You're going to be surprised at how easy it can be to have a very nice lawn, so here goes. The following is fairly generic with some attempt to expand outside of Indiana.

Watering

Water deeply and infrequently. Proper watering is your first line of defense against weeds. When you water deeply you will not need to water every day. Weed seeds LOVE it when you water every day. If you don't water for a week or two (or three or four), then the weed seeds cannot germinate. So just doing this right will save you the cost of all the herbicides (eventually). Deeply means a full inch all at one time. Measure that by putting out cat food or tuna cans and turning on your sprinkler. Time how long it takes to fill all the cans. Mine takes 8 full hours. It can take as little as 20 minutes, so time yours carefully. Then remember that time because that will be the time you water every time you water from now on. Infrequently depends on many factors but is so closely related to air temperature that you should start with this guideline: Above 90 degrees - once per week. Above 80 degrees - once every 2 weeks. Above 70 degrees - once every 3 weeks. Below 70 - once every 4 weeks. If you start now with that schedule then by July your grass will have developed deep roots which can withstand the summer heat and go a full week without watering. There are very few exceptions to this rule (Las Vegas area because of soil, aridity, and heat). Improper watering is the cause of many lawn issues, so get this right.

Mowing

Most grasses do best when mowed at or near the mower's highest setting. The exceptions are bermuda, centipede, and creeping bentgrass. Those should be mowed at the mower's lowest setting. Mulch mow once a week unless you have bermuda. That needs to be mowed 2x and sometimes 3x per week.

Fertilizer

You mentioned Scott's. I believe they are selling you more stuff than you need. It sounds good when you hear it, but you don't need all the stuff they push. One of the elements of lawn care which has come to prominence since the late 90s is the importance of a healthy "soil food web" in the garden. We're talking about microbes (bacteria, fungi, protozoa, and microarthropods). These critters need food to thrive and develop a healthy soil for you. So what do they eat? They eat food. If you look at the ingredients on a bag of organic fertilizer you'll see it contains wheat, corn, soy, alfalfa, and some animal byproducts (chiefly feather meal and poultry litter). All these materials are food for the surface layer of soil microbes. Lower layers live off of the waste products from the upper layers of microbes. After going through 3 weeks of microbial processing, the food you put on the soil is converted into natural plant food for your grass and delivered at root level. You don't have to do anything! The Scott's 4-step products don't have any microbial food in them so your soil can become less than healthy as the food is depleted. In fact the insecticide in their product actually kills the microarthropods...because they are insects. Wiping out an entire class of species in the food web can throw off the balance of nature until the species eventually return. All this is to help get you over the hurdle of using organic fertilizer. Most of the lawn gurus are using organics; however, they are not necessarily buying organic fertilizer. It turns out you can buy the ingredients at your local feed store for about 1/6 the cost of commercially bagged organics. The application rate is from 15 to 20 pounds per 1,000 square feet. If you accidentally double that rate it will not hurt the grass, so there's a huge safety factor built in. Or, if you want to use chemical a approach anyway, someone can help you with that, too. How often you fertilize depends on what approach you take and what grass you want.

Soil testing

If you want to have the best lawn on the block, or if you are having trouble growing any lawn at all, then you need a soil test. The only place to have that done is Logan Labs in Ohio. Sure you can get it done locally, but for $25 the test you get at LL will be much MUCH better than what you get at your local university or county extension service. If you do that, post your results here and morpheuspa can help you understand it and tell you what to get. Good soil tests are necessarily complicated.

Cleaning up bare patches and turning them into grass will depend on what your grass is. Answer the questions at the top of this post and we can help you more.