For sellers, Gunbroker works fine, but of course there are fees. I’ve had great luck posting on specialized forums in their free classifieds.
Obviously, this works best where you have guns that match the interest of the forum. I’m a handgun hunter, so I’ve made quick sales of several hunting handguns on these types of forums.
Gunbroker and most forums have a FAQ about “How to sell and ship guns” that covers all facets of selling, shipping, and completing transactions legally.
I’ve also consigned some guns, but my advice here would be go only with known high volume dealers who can quickly move guns.
Lastly, you have to be able to accurately grade the condition of a gun AND then price it according to area and market conditions. The majority of private occasional sellers tend to over-grade and over-price their guns. The NRA grading system describes in detail what must be present to achieve a given grade. If you’re not really sure how to assess the condition other than a subjective opinion, I’d suggest having someone who knows the NRA system give you a grade opinion and WHY and then go on from there to set the price.
Grouse