Buy in shops
For outdoor gear, I buy items in shops. Given how shipping prices are going and the time it can take, I would want to make sure something fits. Photos on a web site are likely wrong for clothing as changes get made all of the time from the article used to create the photos (if they aren't just CGI/AI these days). The big issue I've found are pockets in odd places, openings, zips and cuts that just don't work for what I want. Handing in a bunch of sensitive information to a vendor I'm not going to buy from very often is an issue as well.
To buy things on eBay, I introduced errors in my information that must be corrected or payment will be denied. The debit card I have has a registered address that's different than what's in eBay's system (different street address, different post code). At first, this was not planned, but when I was going to get everything "corrected", I saw how useful it was and how little time it takes for me to type in the correct information. Both addresses are valid addresses for me with one being a family member's home so if there are notices or packages sent to the wrong one, I'll get them with very little delay. Convenience has a cost.