A blind hem is exactly what it sounds like: a hem with stitches you barely notice. It's perfect for window coverings or anywhere you want a clean finished edge. When I first started sewing, attaining a perfect blind hem was like finding the Holy Grail. And then a funny thing happened, I practiced it a few times, and realized it was really easy. It's sort of like learning to use chopsticks – at first it seems so awkward and difficult and then, suddenly, it's second nature. Try a blind hem and you'll never drop a wad of sticky rice in your lap again.

First, you will need a blind hem foot. This is a special foot that comes standard with most sewing machines. The foot looks basically like this, although it will be slightly different depending on the brand of your sewing machine:

Notice that black part in the middle of the foot (it may not be black on your machine's foot). It's called a "flange." This is your new word for the day; try to work it into a conversation. The flange acts as a guide. It will rest against the folded edge as you sew to maintain a straight seam and make sure the space between the main stitches and the blind stitches is accurate.

Enough Semantics, Now How to Actually Do the Stitch

Make a simple hem

1. Figure out how big a hem you need to get the finished length you want. Most people prefer to err on the side of narrow over wide so there's less bulk to the folded fabric and the hem will lay nice and flat. In fact, it's often better to trim your fabric just a bit rather than make a giant hem.
2. Let's say you have 2" to work with. First, fold in your raw edge ¾". Then, make another fold 1¼". Your first fold rolls inside the second and you end up with a nice folded edge on both the top and bottom.
3. Press hem.

Pin your hem

1. Notice of the position of the pins in the fabric. It is much easier if you place the pins with the tops facing toward your main fabric – away from the hem's edge.
   

At the machine

1. Take the project to your machine. It should be wrong side up, showing that nice folded hem you just made.
   
2. Make sure you have the blind hem foot attached and the machine set to make a blind hem stitch. Refer to your machine's manual to confirm the foot and the stitch number. 
   
3. Fold your nice hem under the wrong side of the main fabric, leaving about a ¼" of the hem's edge sticking out. The tops of your pins will now be pointing towards the machine.
   
4. Slide your fabric under the blind hem foot with the flange resting against the folded edge. When the needle drops it will be sewing mainly into that ¼" of the hem's edge that is sticking out.
   
5. Sew, keeping the flange against the fold. The bulk of the stitches will fall along the hem's edge and every third stitch or so will catch in the main fabric. 
   
6. Open the hem to straighten the seam, gently stretching the hemmed stitches so they lay flat, if necessary. Press. NOTE: I used a contrasting thread for these instructions so you could see my work. You'll choose a thread color that matches your fabric, so the stitches on the front will barely be visible. Blind!
   

You can adjust stitch length if you want less or more stitches catching the main fabric.