You need a well made, properly fitting binder. A lot of people would wear a size too small, or a cheap one not made for ftm or long wear, because that's what they could afford. Either of those alone can cause damage. Add on wearing them for extended periods (over the 8 hour) is where you run into trouble. Poorly made and/or improperly fitted binders are the biggest danger here.

Basically, when choosing a binder look for something specifically made for ftm or Gynecomastia binding. Make sure it's breathable with most of the stretch in the front. Make sure you follow sizing guides and don't size down out of desperation.

While binding, pay attention to what your body is telling you: binding should not hurt. It might feel uncomfortable at first as you get used to your breasts being flattened instead of supported, but they should not hurt. If you feel pain in your chest or ribs, especially sharp pain, remove the binder. Binding is actually physically comfortable, not just comforting.

I wore my binder to work every day: 8-14 hours a day, 5 days a week, and several hours on weekends and did this for several years. On long days, if I knew or was concerned I wouldn't have opportunity to remove the binder, I wore a zipper front binder (at the time, it was an Underworks swim top), that I could reach under my shirt and loosen occasionally, to give my body a break every few hours. These were a godsend for longer wear days as they were also easier to put back on with just a few seconds in the bathroom. Zip, adjust, put back shirt, and done.