Gluten-Free Baking Hints & Tips

Although I haven't been baking gluten-free for very long, I have made a few mistakes and had a few successes. Here's a list of my tips for success, along with some websites of interest:

Bette Hagman is considered the unofficial Julia Child of gluten-free cooking. Be sure to pick up her first book, The Gluten-Free Gourmet and read it from cover to cover. Not only does it have tons of recipes, but it also teaches basic techniques and tells you where you can find the ingredients you'll need to stock your new gluten-free kitchen.
Start Easy - There are a lot of cookbooks and recipes out on the web for gluten-free baked goods. Many of these assume that you have a lot of hard-to-find and expensive ingredients in the house (various flours and gluten substitue chemicals). Before stocking up on all these items, start simple. Try some prepared mixes first so you learn the consistency of the the batters and doughs and the differences in baking time and product handling. Here are some mix companies I recommend. Most of their products can be found in your local health food store or purchased online:
Accept Help from the Experts - Once you're ready to break away from boxed mixes, try using prepared "baking mixes" or "pancake mixes". These are well-tested and incredibly stable flour mixtures that usually include a levening agent like baking powder, as well as Xanthan Gum or Guar Gum as a gluten substitute. They're often used for pancakes, muffins, and breakfast foods, but can also be used for things like cookies and as a substitute to wheat flour in some of your favorite recipes. I always start with a baking mix as a cup for cup substitute when starting to convert a new recipe and go from there. I highly recommend the pancake mix from Pamela's Products, Inc.. However, it tends to be difficult to find and very expensive to be using cup-for-cup. So, I'd recommend Bob's Red Mill's Pancake Mix as a viable alternative. I DO NOT recommend Bob's "All Purpose Flour" because it contains bean flours that are too heavy and cause most baked goods to collapse and take on a vegetable flavor. Note that you may notice a slightly grainy texture in cakes made with Bob's mix simply because it contains corn flour.
Keep it Simple - Ready-made baking mixes can be a bit expensive, so you may eventually want to start making your own. Start with Bette Hagman's basic flour mix and modify it as you learn what works and what doesn't. I recommend this particular mixture because it only has three ingredients, as opposed to others that have 5 or more. If you've had good luck with a prepared baking mix, try adding a teaspoon of baking powder and a half-teaspoon of Xanthan Gum to every cup of Bette's flour mix. The Xanthan Gum will serve as a substitute to gluten.
Save the Bread for Last - Classic sandwich bread is perhaps the hardest thing to master. I still haven't managed it. This is because yeast breads rely heavily on the elasticity that gluten provides to maintain their "poofy" structure. I highly recommend sticking with prepared sandwich bread mixes until you've mastered everything else first. There are some excellent ones out there and you can add ingredients to make different kinds of bread or use them to prepare foods such as grilled cheese sandwiches, french toast, or garlic bread. I've worked with Gluten Free Pantry's "Favorite Sandwich Bread" and had amazing results. Also, there's no need to go out and buy a fancy bread machine. The "by hand" recipe is quite easy to follow, especially if you have a good electric mixer.
"Made in China" isn't a Bad Thing - As you begin shopping for gluten-free ingredients, you'll find that many of them can't be found at an ordinary grocery store. Shopping at natural and health food stores can be difficult on your wallet. Many of the ingredients such as rice flours, rice pastas, and potato flours and starches have been used in Asian cooking for years. Find an Asian market near you. Most large cities have one tucked away somewhere. Make regular trips to it to stock-up. I've found bags of rice flour for as little as 69 cents a package where they'd be over three dollars at a natural foods market.

The hispanic foods aisle can also be a big help. Mexican, Latin American, and Spanish food often contains corn and rice, so you have a good chance of finding products there that you can use. Goya makes some excellent products and they're usually quite inexspensive.

Beware, however, that these items usually make no guarantee of being 100% gluten free. You are running the very minute risk that the grains were processed in a facility that also processes wheat products and there may be small residues in the flours. In general, I have not run across any issues but it never hurts to be careful.
It's all about Structure - Gluten provides an elastic consistency to traditional doughs and batters and a structure to hold the air bubbles produced by levening agents (baking powder, soda, etc.) and yeasts. Gluten substitutes (such as Xanthan Gum or Guar Gum) can help with this, but usually only go so far. Cakes, cookies, and other non-yeast items rely more on fats and eggs to provide structure, so they're easier for a beginner to work with. If your cookies or cakes appear flatter than normal, I've found it helpful to double the levening agent. Keep in mind that in the case of cookies, this could make them more "cake-like".
The Freezer is Your Friend - Freshly baked gluten-free products are brittle if left out and become too moist to handle when sealed in plastic. Freezing or refrigerating seems to solve this problem and assurs that you have tasty cookies, fresh sandwich bread, or cakes whenever the urge hits you. Many cookie batters can be frozen into "ready to bake" lumps as well.
Baking Time - Gluten-free products may need to bake slower and at a lower temperature than normal. Use traditional testing techniques to adjust your cooking times (i.e. toothpick in center of cakes, knocking on yeast breads, etc.).
Cooling - Gluten-free products are usually softer right out of the oven and break easily. Cookies should be made on baking (parchment) paper to prevent sticking/burning and you'll want to let them sit on the tray for 2-3 minutes to firm-up before removing them to wire racks. For cakes and non-yeast breads, lining the pan with baking paper and letting it cool in the pan for part of the cooling time will help you get the item out in one piece.
Don't Over-substitute - I've read a lot of gluten-free recipes and checked out tons of gluten-free products at the store. The problem with most of them is that they try to solve too many problems at once (i.e. gluten free, lactose free, sugar free, etc.). The surefire way to make something taste like "diet food" is to make it vary too much from the real thing. When substituting ingredients, only substitute those ingredients you need to. Likewise, choose recipes that require a minimal amount of substituted ingredients. The fewer substitutions, the better your baked good will taste.