I have been reading posts about dry dog food. 

If I am going to the store to choose a new dry dog food, what ingredients should I look for?  What would good ingredients be listed as?  What should absolutely be avoided?

IMO meat should be the FIRST ingredient, the less cereal the better.  Go for one of the premium foods such as Royal Canin, Arden Grange, Autarky or James well beloved.
Dawn.

Autarky actual has more grain than anything else. However I got round this by feeding my own additional meat.

I don't think you will find many food with more than 50% meat in the adult formula.  the puppy Arden Grange (and Autarky do) and the only adult one is Arden Grange Prestige.

Darling there are any books written on this but off the top of my head I would say that you should find an existing bag of dog food and look up all of the ingredients to see what they mean. they will be listed with the biggest quantity first so if it is something you dont think your dog should be eating dont buy that food! Mainly there will be some sort of meat or meat by products, mechanically recovered is the best that you are likley to get in dog food. then some sort of grain to provide bulk, the best have oats, brown rice, infact the sort of grain a human would consider most healthy. There may well be beet to add bulk and sweetness, although it should not be wel up the list and some sort of fat may be added, idealy it should say what sort it is eg, chicken or vegetable. For me it is normally the last ones on the list that bother me as they are generally the ones that are added to aid processing or storage rather than for the benifit of the dog! 

Ok, we switched food.  I found a dry dog food for sensitive stomachs, no by products and etc.  I am worried about switching around so much.  I went from one food because she was shedding volumes to this.  The brand we used before but the new flavor because I thought the ingredients seemed better.  Now, the shedding is lessened, but she is scratching her neck and around her mouth?????????  This is a new behavior  Is that food related too?   I am so frustrated. 

We went from Purina Pro Plan Mainentance (chicken) to Eukanuba (caused major shedding) to Purina Pro Plan Natural Turkey & Barley Formula Extra Care.  It advertises no poultry by products, no ground corn, no wheat, Real turkey is the #1 ingredient.  26% Protein 16% Fat.  This is the first food we have fed to her that she seems eager to eat.    There is much more information on the package, and etc.   Just completing the transition to the Turkey and Barley Extra Care. 

Here is the other factor.  It is very cold here.  This morning it is only 7 degrees Farenheit.  So, the heater is always running, lots of dry air.  Could it simily be dry skin and not food related?  If so, any suggestions on how to manage that situation.

It cant hurt to supplement her diet with salmon oil and vitE,you can buy them in any healh food shop in capsule form.

Most raw and homecooked feeders supplement with these 2 things,your dog would need them even more because of the dry kibble diet which can wreak havoc on some dogs skin and coat.

Have you had a look at eaglepack dog food,it is a holistic,all natural food and is of a much higher quality  than pro plan.If your dog was doing well on P.P she wouldnt be having coat probs,if you choose to continue and things dont sort themselves out you can check out eagle at http://www.postalpets.co.uk