Some celiacs are hypersensitive to gluten so in order to avoid cross contamination, gluten free foods should be prepared seperately from regular foods. That means scrub every surface before you begin. Use separate pots, pans utensils ( clean ) and do not bake gluten free foods in the oven , while also baking regular foods at the same time ( not even in separate containers)
The other thing to remember is when you are making regular foods, if for example you use the measuring cup in the bag of wheat flour, then use the same measuring cup to get some sugar, without washing it first you have just contaminated the whole bag of sugar so it can't be used for a celiac !
The same goes for things like butter, jam , mayo etc . It is advisable to have separate containers of condiments for the gluten free person in your house .
It gets easier as you get used to it.
The other trick is to be sure the brand you are using is gluten free to begin with. some brands of baking ingredients are gluten free ( GF) while others have gluten hidden in them under other names, like HVP, or modified food starch. Read labels carefully ! It is like a science experiment at first but it does get more automatic, the more you work at it , just like anything else, practice makes perfect.