Principles to remember
If in doubt leave it out. - This one is hugely important. There are a lot of trial and error mistakes you can make. Unless you know what is in a food, don't eat it.
If gluten touched it, it's no longer safe - My child would come home throwing up (her reaction to gluten) at night because the lunch lady at school wouldn't change her gloves to make a salad.
Step 1: Safe Foods
Bear in mind that how these foods are cooked can make them unsafe. For instance fish is safe but breaded fish would not be. You also have to be very careful about food cooked in a fryer. If they are used to cook other non-GF foods, they should be left out.
I'm only including things that may be common in anyone's kitchen. This is partly to help with finding foods you and family might be familiar with.
Food groups that are safe
Starches that are safe
Potato (baked mashed etc)
Common cereals that are safe
Fruity and coca pebbles
Rice chex are now safe
Take out food that is safe (as of this writing)
Burger King Fries (they have their own dedicated fryer and don't coat with wheat starch)
Burger King Milk Shakes
Wendy's Burgers without the bun (Fresh patties means they're not dusted with wheat starch to separate them.)
Wendy's Baked Potato
Most take out salads (croutons are normally in their own pouch) but watch out for the dressing
Hot Dogs without the bun are usually safe
Red Bridge beer made with Amaranth and is labeled Gluten free
Wine (all except possibly spiced wines)
When going to a restaurant ask if they have a gluten free menu. Many are starting to, some have menu items that are marked gluten free.
Update. We recently ran across Dinty Moore Beef Stew and found out it's gluten free!