Excellent article! I worked almost 31 years in warehousing, much of which were stints in Shipping & Receiving, and had to deal with Returns (btw, the correct term for returning items is Return; we and our vendors never referred to Returns as RMAs, which is just a number, as the article states, or a document with the number). I just want to add a few more tips.
When writing an RMA number on a box, cover the number with clear packing tape to help ensure the number doesn't get obliterated in transit. Make sure it is large enough to be easily seen. Using a ball point pen or fine point Sharpie isn't going to cut it; use a large felt pen marker. Protect the shipping and return addresses the same way. Make sure the sipping address is large enough to be easily read and is on two different sides of the package, same as the RMA#. If not using a preprinted shipping label, I always put the RMA number with the shipping address.
It's generally a good idea to enclose a document that has the shipping address, return address, and RMA number inside the package in case the outside is damaged to the point of being unreadable. That was standard operating procedure where I worked.
Pay very close attention to the vendor's shipping instructions. Some require the original packaging (I keep all my original packaging on everything I buy at least until the warranty runs out; it's cheaper than trying to scarf up a suitable box even if the vendor doesn't require it). Using the original packaging will help to ensure the vendor can't try to refuse a claim due to damage caused by poor packaging. Some send a document to you that has to be enclosed in the package or put in a pouch on the outside of the package (we did both on all returns when I worked S&R whether it was required or not).
Even though a vendor may not require it, all returns should be insured. Very few vendors, if any, will take responsibility for damage induced in transit, even if they paid for the shipping, unless they also paid for insurance (check with the carrier when dropping off the package). Taking photos of the product before packaging and of how it was packaged will make favorably resolving a damage claim much easier. Also, putting a tiny mark (just a tiny, unnoticeable dot with a fine point Sharpie on the product itself will do) and taking a photo of that will help to protect you from vendors switching products and use that as a basis to refuse your warranty claim or returning an unrepaired or unrepairable item and claiming it was replaced (it happens).
If a vendor sends a prepaid shipping label, just don't drop the package off at some collection box or drop off point. Take it to the carrier's facility and get a receipt and tracking number. You will need the receipt to file a damage claim against the carrier if the vendor doesn't receive the package. The tracking number will help protect you from a vendor losing a package after receipt and claiming they didn't receive it or received it too late.
There is one thing in the article I disagree with. If a product is received DOA, it should be replaced with a new product, not a refurbished one. That's one reason why a new product should be inspected immediately upon receipt (never sign for a damaged package without getting the carrier to document the damage) and tested as soon as possible after receiving it since the window for justifing the demand for a new replacement product is usually very narrow (often only one day).