First, Barbie's head needs to be reattached to her body for easy handling.  Then, after a very careful haircut, comes the styling.  If you've had the nerve to cut that beautiful hair you've so meticulously rerooted, this part should be a breeze.  The finished product is getting closer, and will be well worth it.  Gather around the kitchen sink, and let's go!

Preparation for Styling Barbie's Hair
After rerooting, measuring, and cutting, it's time to relax the hair so it will properly lay down on Barbie's head.  I comb through her hair to remove any small tangles, and make sure the part is in the properly thatched position.  Then, Barbie goes into the sink upright in a Kaiser stand.  I pour just boiled water over Barbie's hair in the direction I want the hair to lay (in this case, toward her toes).  After the boiled water, I pour ice water in the same direction.  I read in Barbie Bazaar September 1996¹ that the style will hold better, curled or straight, with the hot and cold treatment.  I've never questioned how or why this process works, I just do it.  
(Doing the Do: Ponytail, Starner p. 76)

Straightening Hair for TNTs
To begin the TNT hairstyle, the "sides" have to be pulled up into a mini ponytail.  These are the plugs at the side of the face and back to the ear that are so close together, and were a pain in the neck to reroot.  This covers the bald spot behind the bangs that I was so tempted to fill in with extra plugs. (I didn't.)  I make sure to leave some strands forward of the ponytail on the left side of the part, as they will be an important section of the bangs.  The little ponytail is secured at the top of the head with a 3/16" orthodontic rubber band.

I use styling gel to curve the top bangs to the side, perpendicular to the part, and over the right side of the pulled-up ponytail.  This will cover the rest of the area with no plugs.  I gel the front bangs down against the forehead.  The strands on the left side of the part are curved slightly toward the ear.  The bangs over the left eye will be too long but they can be trimmed later, after the hair is fluffed.  Trimming them now, while they're flattened with gel, will make them too short.  I speak from experience here.

I wrap the head with plastic wrap to hold the bangs and ponytail in place.  I place Barbie back in the sink in her stand, and pour more just boiled water down over her, followed by another dose of ice water.  I blot the hair with paper towels, then place her, in the stand, over more paper towels to dry upright.  After at least 24 hours, I unwrap the head.  With all the water raining down on Barbie's head, the gel is usually pretty much gone.  I comb out the bangs to fluff and shape them a little, then trim as needed.  My Barbie is now ready for a tiny bow to match her outfit.

Styling for the 1969-70 Barbie Flip TNT
According to what I've read in Barbie Bazaar  November 1996¹, all this takes is a couple of tiny curlers and some bobby pins.  Just roll the hair up, towards the top of the head, secure it, and plunge the head in boiling water.  I used original Barbie curlers and bobby pins from her Color 'n Curl set, but I have yet to make that work to my satisfaction.  What I ended up with was straight hair with horizontal banana curls.  That, to me, is not the flip hairstyle on a TNT Barbie.

After much fussing around with curlers, pins, boiling water, etc., I decided to try a curling iron.  On the low setting, I find it to be safe for the TNT hair.  Too bad Clairol never made a miniature hot roller set (remember the Kindness 20 set?).  When I used to set my own flip, I rolled the hot curlers down, not up.  So I curled Barbie's entire head of hair down, little curls all over her head.  Then I flipped the hair up as I combed, and it worked.  Marlo Thomas!  I put a rubber band around Barbie's neck, over the flip to keep it in place.  I don't use hairspray on my Mod girls, but many restylers do.  It's a personal choice.  Now, I'm not the best at doing this hairstyle, but I'm somewhat satisfied with the results.  Feel free to email if you've had success with another method.