silly but useful measurement rules: yes, you'll need a measuring tape or a piece of string that you can measure with a ruler
1. ask questions if you're unsure of the item's condition or measurements. people are usually pretty friendly if you approach them nicely. and, who knows, you might make an internet friend.
2. I compare garment measurements to a similar garment that I own and love. i.e. compare dress measurements of the 1950s dress to dress measurements for my favorite dress with a similar cut/style.
Some measurements are given when the garment was on a mannequin and others are of the garment lying flat ... boring but important difference. garments measured lying flat require doubling the measurement for: the waist, bust, sleeve opening, hips
shirt/jacket: shoulder (seam to seam), bust (armpit to armpit), length (top of shoulder to bottom of shirt), and sleeve length (armpit to end of sleeve)
dress: shoulder (seam to seam if there are shoulder seams), bust (armpit to armpit), torso (top of shoulder to waist seam), waist, hips, sleeve opening, length -- I also care about how the dress fastens: buttons? zipper?
skirt: waist, hips, and length. I like it when skirts fit around my natural waist (the narrowest part of my torso) and fall to just beneath my knee. and how does it fasten: wrap around? buttons? zipper?
blouse: shoulders (seam to seam if there are shoulder seams), bust (armpit to armpit), length, sleeve length, sleeve opening
pants: I'll be totally honest, I'm not brave enough to buy vintage pants over the internet. I can hardly find pants that fit semi decently when I'm actually trying them on
shoes: width across the widest point of the toe, the length from heel to toe
boots: width across the widest point of the toe, the length from heel to toe, circumference of the boot opening
