I don't use reddit. I'm a total internet geek, but just don't quite get reddit's format or how to use it. Perhaps with a little more effort I would get there.
On The Bell Tree forum, and in the amiibo card trading Facebook group, I have done a handful of trades. Not a ton, but I would guess around 10. Each one has gone as planned.
I do like the feedback system here on TBT. Feedback ratings will typically help you figure out who you're dealing with. Be it on the buyer end, or seller end. Maybe not exactly, but it'll give you a good idea. I can't imagine somebody taking the time to build up a strong forum reputation on TBT forums, just to steal a card or two from someone else a month or two later.
The thing about trading these cards, is honestly, none of them are THAT valuable. Individually. Other than the 2 Japanese-only CP promo cards, these cards are like a dollar or two in value, at the most. So to go through all the trouble of setting up a deal just to scam someone for a buck or two, just isn't worth it. And on the other hand, IF, and this is a big if, but if you were to have someone not follow through, and they took your couple cards, you're really only losing out on a buck or two. The principal of someone doing that would certainly be very irritating to say the least, but what you're actually losing out on isn't very much.
So that's why I feel safe doing these trades, specifically on TBT forum, and shipping (and receiving) these without tracking numbers. Unlike high value eBay items that I buy, or something expensive on Amazon, I always want tracking information.
And also my advice, don't worry about giving out your address. If you're under 16, I would ask my parents first just so they don't get mad at you for not asking, but someone who is attempting to trade low value amiibo cards isn't going to come to your house stalk you

Whatever horror movies or media outlet that's stirring up the idea that the internet is full of monsters & criminals is pretty inaccurate. Just like anywhere, there's sure to be some bad apples here or there, but the major majority of it is people like us.
Make some trades, have some fun. It's exciting when the package/envelope does show up, anyone else who's traded will attest to this. I completed series 1 doing this and am looking forward to getting all the rest soon!
- - - Post Merge - - -
don't do too many at once or have a good system to keep track.
I also like this advice. I too, had just 3-4 trades going all at one time, and got myself confused with who was sending what, from where. I even contacted the wrong person when I thought their cards arrived, but theirs hadn't. I got it all straightened out & everything worked out, but it's a good idea to make sure you're keeping close track of what's going where. Wouldn't that be a shame to ship the wrong cards to the wrong people
I'll always make sure a person gets their promised card.
And this as well. Do your best to ship promptly! On the receiving end once, a trade partner took forEVER to ship theirs to me. And I waited around for quite a while, unsure of what was going on. It did arrive eventually, but he took a long time to ship it & I didn't think that was very polite.