This page is a catch-all for notes on various candy ingredients. It is vitally important that all ingredients are good quality, and fresh. Time and care taken to examine the ingredient list of your ingredients-to-be is well spent.

In almost every case, you'll get the best results if all ingredients are at room temperature.

Chocolate Chips
Good quality chocolate chips should be made from only a few simple, natural ingredients - Chocolate, Sugar, Cocoa Butter, Lecithin, and Vanilla are the common ingredients in many chips. Stay away from ANY chips that contain any added colors or flavors, paraffin (wax, a filler) etc. (Don't even think about making candy with 'chocolate-flavored morsels'...) My personal favorite for making fudge is Ghirardelli Double Chocolate 60% Cacao Bittersweet chips. (since they come in 11.5 ounce packages instead of 12 ounce, use a slightly smaller amount of marshmallow fluff to get the best results)
Sugar
Always use 100% pure cane sugar for candymaking, unless a recipe specifically calls for something else. Many 'house-brand' sugars contain a percentage of other sugars, like sucrose, that are fine for sweetening, but totally ruin candy - stick with a major brand of granulated cane sugar and you'll be fine.
Marshmallow Creme
I hate to say it, but even though I usually use a variation of Kraft's fudge recipe, I do NOT usually use their marshmallow creme. Why?? Well, as with chips, I feel it's important that the ingredient list be simple and natural. Quite a few marshmallow fluff brands (including Kraft since about 2002) now add a variety of adjuncts to their product, usually including artificial colors like FD&C Blue and/or Titanium Dioxide (a white food coloring). No, thanks.
Butter
While most recipes indicate the use of butter or margarine interchangeably, I always use real, genuine butter. To me, flavor of the resulting candy/cake/whatever is far more important than an evanescent belief in the health effects of butter vs margarine, and I've also found that most margarines (even if they avoid extra ingredients) don't deliver as good a texture in candy as genuine butter does. That said, if you are concerned over the health aspect of butter vs margarine (in which case you probably shouldn't be baking too much anyway... ;^) go ahead and use a good quality margarine instead, as a direct replacement for butter. Regarding cost, I consider it well worth the extra expense for real butter, but to ease things somewhat I always stock up when butter is on sale at the market, usually keeping 3-4 pounds in the freezer.
Vanilla extract
Here again, I strongly urge you to use real Vanilla extract, not an artificial vanilla flavoring. The 'fake' vanillas are certainly suitable for most baking & candymaking with no real problems, but I prefer the resulting flavor imparted by genuine vanilla, so I just keep real vanilla on hand. In actual practice, I usually use double-strength vanilla extract, which you usually will NOT find at the market - I get mine from TheSpiceHouse.com. (who offer an incredible selection of very high quality spices, herbs, flavorings, etc - I cannot recommend them highly enough.) Double-strength vanilla is just what it sounds like - twice as strong, so you can use half as much to achieve the same flavoring. This can make quite a difference in some cases, such as a white cake with snow white icing, where a few teaspoons of vanilla extract can result in a noticeable yellowing of the supposed 'white' color.
Nuts
For fudge, the most common nuts are either pecans or walnuts. My personal preference is for Black Walnuts, although many people don't know what they are. (Diamond brand nuts offers black walnuts, although most markets don't carry them it seems.) 'Ordinary' walnuts are actually properly known as English Walnuts. Black Walnuts are a stronger flavor (much stronger usually) and also significantly softer than English Walnuts. One result of this is that it is extremely difficult to find Black Walnuts except broken or chopped, since it is very hard to extract the soft nutmeat from the walnut intact. (they're also noticeably more expensive, in part due to the difficulty extracting the nutmeat) Once again, fresh ingredients are tremendously important, especially with Black Walnuts, since the oils in these tend to break down more quickly than those in many other nuts. To prolong shelf-life, nuts can (and in my mind, should) be stored in the refrigerator or freezer, but if so be CERTAIN that they are at room temperature before mixing them into your candy - cold nuts will almost always ruin fudge.