There's one thing I do before I go into a thrift store that I think really helps me track down some great finds and it's something you can easily be doing too.
I keep an ongoing Thrift Wishlist on my phone that I add to any time I think of something I'd like to find someday or something I want to be on the lookout for for a specific project. Sometimes I'll even add notes/requirements for the find (like if it needs to fit certain measurements or any features that would be a plus).
Each time I go thrifting, I scan over my list before entering the store just so that wishlist is fresh in my brain. Then I shop like I normally would, not necessarily for those specific things on my list.
I've noticed I'm way more likely to notice things from my list doing this than when I don't look at it before shopping and it's a great way to be a little more sure of whether or not something will work for a project based on those additional notes.
One final piece of advice: don't erase things from the list once you find them.
I check things off as I find them, but I never erase them. It's helpful to have a visual reminder of how many successes I've had from the list instead of an always-growing list of things I haven't found yet. It give me that little bit of hope that I'll check it all off someday.