I prefer stores like Goodwill and church thrift stores over consignment. Reason is, the folks pricing the items at these former places usually have no knowledge of or interest in clothing, whether intrinsically or what people are looking for. So prices stay very low.
Example: I got a tan shoulder bag for a dollar at a church thrift that was genuine alligator from allied-occupied Germany - it had a mark note in it. I saw the same thing offered online for four figures.
I got an unusual black quilted camel hair coat - thickness between a camel's hair sweater and a plush camel coat - with leather collar and pocket bands for five dollars. Extraordinarily lightweight and warm.
Made for a specialty department store.
But at the same time, volunteer staff at church thrifts get notions.
"I know this is good quality because it was my daughter's and she only buys good clothes." (They weren't) Or they may recognize a designer's name and not know the difference from a Target collaboration or the designer's lower end line or licensing of their name. All those things they mark up considerably and I don't bother explaining or arguing and they tend to sit unsold. But also, if you are a regular customer they tend to recognize broadly what you like and bring it out to you.
My wardrobe tends to evolve a lot so I look for trends or colors I want to try. And I do try on pretty much everything. If not in a church ladies room, say, then in front of any mirror I can find and I dress to be able to do this. I notice that most people do not try on and just load up because the prices are so cheap and take their chances on having to donate back.
I also can sew and can do my own alterations and sometimes what my husband calls "remanufacturing" to my own specifications.
ETA: often I'll find sewing or knitting projects people have donated. Usually beautifully made but while they're terrific at sewing, they're not always so good at fitting skills.
I got a cotton tropical print dress with no white in the print. Husband says it's the perfect summer dress and looks like a parrot. I get compliments on this every time I wear it. One dealer told me it was the prettiest dress he'd ever seen. Only it didn't start out as a dress. It was a safari-style romper. And I can tell what happened. The sewist didn't try to sit down in until it was finished and that's when she learned that she hadn't altered to give enough crotch depth. So I just made it into a dress.
Another example is a kind of bland but also beautifully sewn grey and white faux seersucker shirt dress with circle skirt. Once on, it's almost impossible to get off again. So I merely removed the waist elastic and now it's terrific.