If you are trying to be more intentional with your clothes, I have some tips on how to stop buying fast fashion:

I watched the documentary: The True Cost. The documentary is about the clothes we wear, how it is made, and the impact the industry is having on our world. You might have not noticed but the price of clothing has been decreasing for decades, even I am wondering about it. On the other hand, the human and environmental costs have increased. Through the documentary, we would be able to understand the behind the scenes of making clothes.

Declutter often. Decluttering clothes gives us a chance to see or audit the existing clothing items we own. In my closet, I have items that I often wear and love wearing. When decluttering, ask yourself if you have worn the item for the past 6 months and do you see yourself wearing it in the next 6 months. If your answer is "no" for both questions then its time to let the item go.

I shop "basic" items. Ever since I stopped buying from fast fashion brands, I find myself buying more "basic" items like a black shirt or a white tank top. When you have these basic items you can mix and match them with other clothes like cardigans, etc. compared to trendy items.

I shop at local sustainable fashion brands. Most of the time, sustainable brands cost more than fast fashion brands, but they last longer as they are made ethically, made of good or quality materials or even hand made with love. Even my hand made work shoes lasted longer than my past cheaper shoes.
I think of these as investments. If I would have bought 3 shoes at most Php 1000 each (which only lasted a year, so that Php 3000), I would still save money with my one hand made shoes which were Php 2400 and they'd go for 2 or more years.

I thrift shop. Before buying from sustainable fashion brands, I was once a broke new grad. I was living in an expensive city and barely saving any money All I could afford was thrifted items for my apartment. But I found great finds and 95% of the ones I thrifted before are still my favorites and are still in very good conditions.

I follow the 30-wear pledge. When purchasing clothes, I ask myself "Will I wear it a minimum of 30 times?" If its a yes, then its sold!