1. Don't pay attention to sizes
This is always my first rule. Sizes in thrift stores are almost meaningless. I've thrifted things in so many different sizes it's ridiculous. Not only do thrift stores feature items from a lot of eras with different sizing standards, but they also have stuff from tons of companies with their own unique sizing. So while you might be a size 8 in modern clothing, make sure you don't ignore the sizes around the 8's because you'll probably fit into a lot of sizes! Plus, you can always find something that's a little to big or small that will only need minor alteration to make it work! The dress above was quite big on me, but I loved the vintage floral print and pleats, so I pinned it to make it fit.
2. Go regularly
Thrift stores are always putting out new inventory, so it pays to go in frequently. It's also nice to know what day they typically restock the store, so you can go in and get first pick of the new inventory.
3. Look at things with their potential in mind.
Sometimes I'll just love something because it has an awesome print or cut, but it's too long, or too big, but I know with a little alteration I can make it into something totally workable. The pleated skirt below used to be part of a little girls' school uniform jumper. I cut the jumper part off and it was the perfect navy pleated skirt!
4. Spend time.
There are a lot of ugly things you have to sift through in order to strike gold. Be sure to take the time to go through the racks thoroughly so you don't miss the diamond in the rough!
5. Try new styles.
Because thrifting is so cheap, you can afford to try a new style or trend that you aren't sure will look good. For example, I recently got the urge to try a maxi skirt. I was uncertain if this style would look good on me, so I headed to the thrift store to find an inexpensive maxi skirt to experiment. Lo and behold, I love it! But if I didn't love it, I'd only be out $4.00. No harm done!
6. Check for sales.
The thrift store that I regularly go to has 99 cent mondays where each monday a different colored tag is 99 cents! This is pretty exciting when you fall in love with something that just happens to be on sale that day! Find out when your favorite thrift stores have sales and be sure to stop in on those days.
7. If you know you can find it thrifting, don't buy it new.
This is my own personal policy. I won't buy something brand new if I know that I can just go to the thrift store and get it for super cheap. This applies to a lot of things. Pretty much all my kitchen stuff is thrifted. Works just as well and is way less expensive than buying new.
8. Try things on.
This goes hand in hand with ignoring size tags. I will pretty much always shop from the size 0's through the size 10's. Sometimes I can tell if something will fit, but with thrifted stuff it's hard to know. Trying things on can also help you to figure out if you can alter it to make it fit better or if it's just a lost cause. The skirt below has a size tag on it that is at least 3 sizes too big for me, but it fits me perfectly!
9. Shop the whole store.
Shop the men's section, the kids section, the women's section, etc. I've found large little girls dresses that fit me perfectly, men's cardigans, little boys' t-shirts, and so on. Don't limit yourself to the women's section just because that's where you shop in normal stores. There are lots of good things hidden amongst other sections!
10. Wear something that is easy to take off & put back on.
Sometimes I forget this when I go thrifting and I have some elaborate outfit with multiple pieces that takes 2 minutes to take off and put on. When I have on a complex outfit, it makes me so much less likely to want to go into the changing room to try on something. Such a drag!