Start with clean, well conditioned hair. Shampoos, conditioning cleansers, and conditioners made for ethnic curls are great for this purpose because they provide very deep moisture and help prevent frizz. Unless your hair already tends to be super oily, don't be afraid of using products that are a little more dense than you're used to: pin up styles emphasize a lot of shine and control.
When your hair is almost completely dry- think dry in appearance, but a touch damp when you run your hand through it- you'll want to start working.
Active Time*: 35-45 minutes setting, 25-35 minutes styling.
Idle Time: 2 to 8 hours (Take a nap, watch a movie, or go to bed and sleep with them in)
*Active times are based on the consideration that you may be working at a leisurely or careful pace. With practice and experience, the style can be completed more quickly.
The technique is pretty simple.
You'll work in sections, taking a single chunk of hair at a time. The bigger the piece, the looser the curl, so if you're going for lots of tight curls, use smaller sections, or large sections for soft, bouncy waves.
After you've gathered a section of hair, spritz it with a little setting lotion and comb it through. Then use your fingertips to curl or spiral (again, depending on the type of curl you're going for) the section of hair to your scalp. Use a styling clip or a bobby pin to pin the curl into place. Repeat with more sections, going around your whole head, until all of your hair has been pinned into place.
Simple, right? Now you'll want to let the curls set for a little while. If you've done this at night, it's particularly easy because you can just go to bed.
When it's time to take the pin curls out, do not panic. You're probably going to look like you have bad, out of control 80's hair. This is the part where a lot of ladies decide that they've done a terrible job and never try pin curls again, not realizing that they weren't actually done. At this point you'll want to use a soft brush and a little styling product to sculpt your hair into place. Emphasis on sculpt. You want to shape the hair, but not actually brush it through. This will take out your curls and leave you with a lot of frizz.
With a little practice, this style can actually be done quite quickly and isn't very much work at all. It has the added benefit of not damaging your hair with heat as well. All of this, paired with the timeless beauty of the finished look makes it pretty clear to see why pin curls were a favorite standby.