I know nothing about Binders

A friend recommended www.t-kingdom.com/ to me, and they and I both own binders from there that fit comfortably and don't cause discomfort. I've heard good things about www.gc2b.co/ too, as their binders are designed by genderqueer people for genderqueer people, but I don't have any experience with them. As for sizing, check the sizing charts of wherever you buy the binder from. Always buy the size you measure in at; don't go a size smaller!! Too small binders can cause damage to your ribs.

Also, don't wear your binder for more than 8 hours when starting out. You'll learn if your body can handle that amount of time, or needs less time in your binder. If you start feeling pain or pressure in your ribs, take your binder off!

Don't be scared off by all of this, though! As long as you limit your binding to no more than 8 hours in a row and get a properly-fitting binder, the chances of you running into trouble are extremely low! I hope this helps!

T-Kingdom style binders can be safe longer-term for someone who doesn't have a lot of outward projection to their chest shape, but as someone with a very outward-going and fairly large chest (32DDD in the useless U.S. sizing system, 30G-H on the more accurate European scale) I can only really safely use Underworks binders.

Google the European method of measuring and check; if you're anything above an E, they may lead to increased risk of cracked ribs or walking pneumonia longer-term, as my friends have experienced. My old Underworks was a hand-me-down that was already broken-in for a friend's different-shaped chest and it still worked well and was reasonably comfortable, but I had to stop wearing it because I went from an F to an H with a lot of extra volume and it was already a size small.

I'll back up the assertion to actually follow the size guides of the binders and do not buy one sized smaller than what they're advertised for. It will end in pain. It may end in someone having to help you out of a terrifying trapped-in-your-binder situation, and at worst they may have to literally cut it off you and take you to the ER.

Other binder tips-- the no more than eight hours thing is a hard-and-fast rule, but when you're new to it, two or three hours at a time is best until you're adjusted. If it hurts more and restricts your movement more than wearing a sports bra, you need a bigger binder. If it's not getting you very flat at all, you need a BETTER binder, not a smaller one. Polyester shirts won't cling to any lumps/curves left by the binder as much. Athletic-cut t-shirts in your size will also be great at masking the binder shape and lending a more masculine silhouette, as will tucking in your shirts to relatively snug-top straight-leg trousers/jeans.

If you try to put on a binder less than a half hour out from a shower, when you're not very very thoroughly dry and your skin hasn't bounced back to its normal texture, the binder will stick to the skin on your arms when you try to put it on and you'll be stuck with your arms over your head struggling until you dry. If it doesn't trigger dysphoria to carry a small messenger bag, do so and keep a comfortable cotton sports bra in it at least the first few times you wear your binder in public-- I always keep a comfortable and somewhat binding bra with me when I bind in public, so that if I have a pain or breathing emergency from wearing it too long, from it being too hot out, etc I can change fast. I always regret not having one with me.

Good luck!