>>58594
I'm an infrequent and fairly inexperienced buyfag everything considered but this is my advice (might not be what you were asking, sorry)
Usually the best way to go is know exactly what piece(s) of merch you want to buy before you shop and focus on that and don't get distracted by anything else. If your waifu's source is really popular, preorder stuff. If not it doesn't matter as much.
Ebay and west-side Amazon are a mixed bag. You can get stuff at a good price occasionally but usually the prices are way too high. You can sometimes get stuff from cons and brick and mortar but I wouldn't rely on this especially because my waifu is from something more niche. Western AmiAmi is great for preorders but afterwards you're probably out of luck. I've heard western Mandarake is good too although I haven't used it. The best way to go in my opinion is to use a proxy or shipping service (or both) and order directly from Japanese websites. I'm guessing you would probably get more mileage out of a proxy.
After that, it really depends on what you are thinking about buying. Is this something new or in stock? Then you probably want to buy from the manufacturer or a shop that sells originals. I've bought from a few different shops, whether you can actually make an account or payment yourself depends on the shop itself. For instance, you can shop on amazon.jp no problem with a foreign credit card (and there's even an option to turn all the important text to English) but most sellers require you to have a shipping address in Japan. That's where shipping services come in.
Basically shipping services allow you to use their warehouse as a post office box. I've used Tenso a few times and don't have any complaints personally. It's pretty straightforward, the only annoying thing is that you do need to show identity verification the first time that you get something shipped.
If you don't want to go through all that hassle of setting up multiple accounts there are also proxy services. I think this is most useful if you want to get something off of Yahoo Auctions (which is like Japan's Ebay) but also the only real way to buy from sites that don't allow foreign credit cards. It is a little more expensive though because usually there are processing fees that aren't there with just a shipping service, but a lot of proxies make it very easy for you and do most of the work for you (many of them let you ask loads of questions if you don't understand what it is you're looking for). Buyee is the proxy associated with Tenso, but there's also Zenmarket, From Japan, Goody Japan, Big in Japan etc etc. I don't have a loyalty to any proxy in particular, just make sure you read the site's shipping terms to figure out which is the best for your purchase. All these sites are in English.
Just a final note, in my experience shipping can be expensive so it's best to do a few major hauls a year as opposed to a few throughout the year, through one proxy/shipping service to save on shipping if possible.
