But if you must indulge, seek opinions from Aml members.
A good topic.
Assume everything is a forgery/other and work from there.
Do not let your collectors heart believe or accept that which you can not substantiate with your eye and numerous period exemplars.
Use skills from every discipline you can apply.
Seek opinions - form your own.
Blind allegiance to people or papers can get you lost.
Education need not include "paying your dues" or be expensive - don't buy until you have the information you need. With very few exceptions, there will be another and another - there is no rush.
My favorite thing you said was "education need not include 'paying your dues' or be expensive." If buyers came to this site or specialty sites like the Star Wars collecting site Rebel Scum, they could almost eliminate their risk of buying forgeries.
Part 2. Under "Things to avoid"...
Poor scans, especially when asking for better. Why?
"Seller does not offer returns" etc - reason for this as well?
Things not to avoid:
Fine print in virtually all auction policies/terms.
Past auction results and images.
Indeed. If a person will forge an autograph, fake COA seem a minor infraction comparatively. Recall the badly executed Beatles album last week with the COA that went nowhere - fake UK address and all. Google is your friend.
What about buying from reputable dealers like Steiner for sports? And certification from JSA and PSA/DNA? Almost all of the top sports auction houses depend on them?
Does anyone get authentication from both PSA/DNA and JSA? It would have to be a pricey item.
Well, I don't know anything about that.
It is known nothing is impervious.
I said "Google is your friend" - should have just said "Research..."
To continue the post, form instincts carefully, from observation and other tangible things, and then trust them judiciously.
"Papers" are just one...beam in a framework supporting authenticity. There are others of equal or greater value I believe. Make sure they are all sound.
This might be obvious, I don't know. Can't hurt to be said. If recent auction results and sales show an item is pulling $250 or so, and it is online for $25 - something is amiss.
If a seller has a preponderance of beautiful glossy color but often illegible recent and popular stars and cast signed items from the popular shows/movies (which are often over-valued and overpriced), and/or a seemingly endless supply of older stars in classic poses especially (usually at lower prices), and those have more in common with each other than accepted and known exemplars - something is amiss.
Other Tips for Holiday Shoppers:
Shop around - you can find the same exact item listed in many places - over there for say $450, over the other place...$299.