Question
After years of paying top dollar we have decided to attempt caring for our lawn ourselves.Saying I am a novice is an understatement. We live on Long Island (NY) and have an acre of property. Last season, nothing was done besides mowing but prior to that the lawn was fed regularly. there are light and dark patches of grass, "bald" spots with hard packed earth, moss and weeds (clover, dandelions, etc.). I'm pretty sure you can't treat for weeds and seed at the same time and some of the entryways to our yard are rather "muddy" with very sparse grass. What do I do....where do I start and what comes next??  Appreciate all of your advice.....By the way, we have a small dog so I need to know how to keep him safe while I treat the lawn.  Thanks.

Answer
The first thing to do is earmark an area where you will have the dog run. Then earmark another area of equal size which he will use while you rehabilitate the first one he has torn up. Whether  you keep these areas under grass or mulch or something else is up to you and your budget.
  "..some of the entryways to our yard are rather "muddy" with very sparse grass." suggests that there are many points of access to your property. Designate one as your main (front?) entrance and concentrate on this area first.
Make sure that you have a plan for watering the area regularly and effectively because it is not possible to maintain a fine lawn without some supplemental irrigation.
Decide on the species of grass you will keep or install and get rid of the rest by either using a non-selective chemical like Glyphosate or else using a machine or manually removing the unwanted vegetation.
Replant or re-sod these cleared areas and pay special attention to them to ensure that they get properly established. In the meantime, as you mow the property, you will define the problems existing elsewhere - weeds, bare patches, off color spots etc. Decide what to attack and do so in an orderly fashion.

Weeds: If you decide on chemicals, identify the desirable turf - right down to the specific variety and choose only the chemicals which are safe. You stand to lose your lawn if you do not follow this simple guideline.

Off-color spots: Try to eliminate "other causes" like the dog, where building materials were buried during construction, parked vehicle etc. If it is indeed a nutritional problem, you might try applying a liquid fertilizer (like Peter's? or liquid iron and see if you get a response. If you do then your best bet is to keep doing this whenever needed. To resolve this kind of problem you will need to do soil samples. If you can afford it, by all means do so; the solution will be permanent, or at least longer term.

Fertilizer: Check with your County and Local Authorities as to what regulations might be in place - and follow them. You want to apply a fertilizer that will build and strengthen the turf.
     It might sound like a lot of work; and it is! But it is interesting stimulating and challenging.