The binding we're making for this quilt is straight-grain double-fold binding. The strips we cut for our binding were cut on the grain, rather than on the bias. There are pros and cons to both straight-grain and bias binding.
Requires less fabric
Is easier to work with, particularly for making sharp corners.
Is useful for binding curved edges
Can be a more interesting way to show off geometric prints like plaids or stripes
May wear longer, since the creases aren't right on the grain
I use straight-grain binding for most quilts and think it's a good choice for a simple quilt like this.
Start by cutting enough 2.5" strips to go around your finished quilt, plus a couple of extra inches. Trim away selvedges.
I usually sew my binding together end-to-end, using a half inch seam allowance. If you do this, be sure to use a slightly smaller than normal stitch to prevent the seam from pulling apart as you work. If you like to make "scrappy" binding using more than one fabric, sewing the strips end-to-end tends to look a little nicer, since the seams are perpendicular to the edges of the quilt.
Alternately, you can sew bias seams in your binding, as shown above. Sewing bias seams isn't strictly necessary, but can result in somewhat less pressure on the seam and more even distribution of the seam allowance.
Use the method you feel most comfortable with. Personally, I think that pieced binding (as in the example above) looks best when sewn together end-to-end. If you're using a solid or a smaller or non-geometric print, the way you sew your binding strips together is going to be less apparent on your finished quilt.
Once your binding strips are sewn together, press the entire length in half with wrong sides together.
You can begin pinning your binding at any point on your quilt. I would just suggest doing it at least a foot from any corner. (As you pin, the raw edges of your binding should line up with the edge of your quilt, wih the fold on the inside.)
If you find that any of the seams in your binding ball within an inch or so of a corner, you may want to unpin everything and adjust your binding to prevent this. Having a seam at the conrner can make achieving perfect mitered corners difficult!
When you come to a corner, you'll need to fold the binding in a specific way in order to make a perfect mitered corner. Start by folding the binding perpendicular to the side you just pinned, as shown above.
Then fold the binding back, as shown above, making sure that the fold is lined up with the edge of the quilt.
Turn the folded area so it looks like the above photo and pin in place.
Continue pinning around the entire quilt, repeating the last few steps at each corner.
When you reach the point where the two ends meet, trim away excess fabric and remove the necessary pins to make your binding look like the above photo. Press the area, creating creases where the two ends meet.
Remove enough pins to allow you to use the crease you just pressed as a guide to sew the two ends together.
Trim the seam allowance to about half an inch and refold, press and pin the binding back in place. You should now have continuous binding pinned all the way around your quilt.
Sew your binding to the quilt. I use a 3/8 inch seam allowance, because I like my binding to fit tightly. If you'd like a little more ease in your binding, you may want to use a 1/4 inch seam allowance instead. If you have a walking/even-feed foot, you might consider using it here. If you don't, you may need to lengthen your stitch and turn up your tension slightly to get a nice stitch through all the layers.
When you reach a corner, sew up to the diagonal fold in your binding, as shown above, and backstitch to secure.
Fold the binding back over the area you just sewed and, starting at the corner, continue sewing the binding along the next side.
Sew all the way around your quilt, repeating the last two steps at each corner.
Turn your binding to the back of your quilt. To secure while you sew, you can use pins or binding clips like the ones shown above. They look and work like hair clips, but are actually designed to hold binding in place while you sew. (Don't put them in your hair though! They don't have the same kind of rubbery guards that actual hair clips do.)
I like to use a "knotless" start when sewing binding. To do this, fold a length of thread in half and thread the fold/loop through a sharp needle. Pull the threads so the loop is at the long end of the thread and the loose ends are up near the eye. Insert your needle into your quilt sandwich near the edge of your binding and pull it back up through the binding, leaving the loop as shown above.
Thread the needle back through this loop . . .
. . . and pull, making a nice little anchor to start your stitching.
Begin sewing your binding down, making a stitch every quarter inch or so. As you sew, make sure that you're pulling your needle and thread through the quilt back and into your batting, but not back through the front of your quilt.
Sew around each corner, folding the binding into a nice mitered corner, as shown. Continue sewing all the way around the quilt, until all binding is secured.
And that's it! Your binding (and your quilt) is done.