Step 1: receive invitation and determine which stores the bride and groom have registered at. (There are usually nifty little cards that indicate the store's name and website. Failing that, it may be written on the back of the invitation. Failing THAT, you can always call and ask.)
Step 2: drive/walk/bike to aforementioned store. (If multiple stores, choose your favorite and go there. After all, you probably want to purchase something for yourself as well. I mean, you're already going to be there... why not take advantage? Consider it part of the "wedding expenses."
Alternate (much easier) Step 2: Log into store's website. This may be boring, but I have found it saves me a LOT of money.
Step 3: Find the inevitable kiosk where you can view and print the couple's registry. Usually near the front of the store. Look near Customer Service. If you see flying doves, or a pastel rattle, you're in the right place.
Alternate (much easier) Step 3: Click on the "wedding registry" link on the store website (usually also marked with flying doves or a pastel rattle.)
Step 4: Find the couple's wedding registry (using the bride/groom's name and state where the wedding will take place) and print it out. (I wonder if it's the "print it out" part where people get tripped up? Look, I know we're all trying to be green and all....but this is important. If worse comes to worst, you can always take the registry home with you and recycle it. (If it's more than four pages long, feel free to judge the bride and buy her a cheap gift.)
Alternate (much easier) Step 4: Search for the online registry using the bride/groom's name.
Step 5: Choose item from registry that you would like to purchase. (My choices are usually governed by budget. Some people like to find something that will make the bride think of them while using it. Don't bother. Of the brides I've polled, many can't even remember if what they're holding was a wedding gift at all, much less who gave it to them.)
Step 6: Take chosen item to the checkout counter to purchase.
Alternate (much easier) Step 6: Click on chosen item on the online registry.
Step 7: Purchase item. (Believe it or not, couples don't usually like stolen gifts. Probably because they don't get the gift receipt to exchange it with.)
Step 8*: (VERY IMPORTANT) Hand registry to cashier.
If these steps are conducted in the proper manner - particularly step 8 - situations where people may purchase duplicate items from the registry (and perhaps have to carry a large bulky blanket halfway across the continent - because it costs money to check luggage - before finding out that it must be returned because someone doesn't know "wedding present purchasing etiquitte") can be avoided. If the person who has to return their duplicate gift happens to - oh, I don't know - know the bride well, and can actually find out WHO the idiot was who doesn't know how to use a bridal registry...well...that might breed resentment and anger.
Just a guess.
I'm pretty sure the bride and groom would also appreciate if idiocy can be avoided and these simple steps are followed because - hello! - who has time to return duplicate gifts? They're on their honeymoon people!
*Note: Step 8 is only necessary if physically at the store. The neat thing about online shopping is that the gift is automatically removed from the registry, so there's no way they're getting a duplicate. Technology - makes even stupid people seem smart.