You're familiar with the mantra - Reduce, Reuse, Recycle?
There is a reason they are in that order as they are listed by order of importance and impact. When it comes to clothing, here's how those R's work.
Reduce - Do I Actually Need This?
If you don't need it, don't buy it. Consume as little as is reasonably possible. I am always shocked to learn that some humans redo their entire wardrobe yearly (or worse). There is no reason to do this. It is extremely wasteful. If it isn't broken, it doesn't need to be replaced. I wear clothes until they are literally falling apart (and sometimes after). If you must buy, buy with an eye for quality. I'm still wearing t-shirts I got two decades ago. They're still in really good condition because they were high quality.
Reuse - Do I Actually Need This NEW?
There are two ways to reuse clothes. One, as your clothes fall apart, repair them. Many repair jobs are very easy to do with even a simple needle and thread. Sometimes, you can turn pants into shorts, or long-sleeved shirts into tank tops to prolong their lives. Two, you can insist on buying used whenever that is reasonably possible. Given there are a bunch of insane humans that redo their wardrobes yearly, you can get a lot of really nice clothes at consignment stores or thrift stores. And for a really, really good price. Plus, you will find a heck of a lot more variety at these stores than you will in retail because every single item there is different.
Recycle - Can I Make Something?
There are places that take old textiles and recycle them. Sometimes you can find local drop-off sites, but there are also some on the internet. If the clothes are in good condition, you can also donate them to the same thrift stores you shop at for the prior step. If you are the crafty type, you gan give clothes that are past their use a new life in various projects. You can make rugs, patchwork quilts, use them as cleaning rags... lots of possibilities!