With right sides together, sew together the two strips of fashion fabric.
Then, sew together the two strips of lining fabric.
This will give you a very long strip of each fabric.

Press the seams open with a warm iron.

Try on one of the strips to determine the desired length for your scarf, and mark.

Lining the two strips up, right sides together, trim one end at an angle at this
point.

Mine is 68" on the longest side; you can keep yours longer if you prefer.

For flat objects (credit cards, ID, etc) a pocket pattern can be drafted
simply by tracing around the object and adding a 5/8" seam allowance
all around.

For thicker objects (such as a cell phone), trace around the object, add
a space equal to the object's thickness all around (in this case an inch),
and then add 5/8."

The result will serve as a custom pocket pattern for all your necessities.

Using the patterns you have drafted, cut the desired number of pockets out of the remaining lining fabric.
Mine has only two, but you can make as many as you need--just be sure that all the pocket openings will point upwards, and won't press on your neck when you're wearing the scarf.

For each pocket, cut a strip of fashion fabric 1 1/2 inches wide, and as long as the top edge of the pocket.

Place these strips right-side together with the pocket pieces, and stitch 5/8" from the edge.

Fold the seam open as shown, press, and turn the edges to the wrong side of the pocket, leaving a small (about 1/4") line of fashion fabric visible on the right side.

On the right side, stitch along the first seam, securing all the loose fabric edges to the wrong side of the pocket.

Fold in the other sides of the completed pocket, 5/8" from the edges, and secure with pins.

Pin to the right side of the lining strip in the desired location, keeping in mind that the outer 5/8" of the strip should be left clear for the seam allowance.
 
Stitch the pocket in place, approximately 1/4" from the pocket edge.

To make a simple pen holder, cut two small pieces of elastic (two or three inches each is plenty).
Fold the ends under and pin the strips a few inches apart--in the example, they are placed towards an edge, so I've left the outer ends unfolded, as they will be anchored by the side seam.

First, stitch down one folded edge of each piece.

Next, push up the centers of the elastic strips so that they form small arches just large enough to hold a pen snugly (as shown), and stitch the remaining edges.
Test your pen holder to make sure the arches are the right size for a pen or
pencil; if they are too loose or too tight, take out the second set of stitches,
adjust the elastic, and sew again.

You'll need to cut a piece of nylon web (or matching/contrasting fabric, if you prefer) about 5 inches long. Fold it in half, thread through the D-ring, and pin in place.
I chose to center it near the bottom of the front (fashion fabric) side, but you can just as easily hide it on the lining side as you did with the pockets.

Sew the webbing in place, coming as close to the D-ring with your stitches as possible.

Once the D-ring and webbing are attached, sew on any decorative trim you plan to use on either front or back surfaces.
You don't need to attach trim that will decorate the very edges of the scarf; this will come after you've sewn the two faces together.

You should now have both faces of the scarf completed: the lining should have all the pockets attached, and the fashion fabric should have its key ring and any decorative trim.

Place the two strips right side together, and stitch along the two long edges and the angled short edge, leaving a 5/8" seam allowance.
Turn right side out, push out corners, and press flat.

Fold in the raw edges on the open end; press flat and topstitch.
This is a good time to sew any trim to the edges; simply pin to the back if you only want the edges of the trim to show (as with lace), or pin to the front if you want all the trim to show (as with eyelet tape).
Then, topstitch to secure.

Trim any loose threads, stash your stuff, and leave your purse behind! What a feeling.

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Note: This pattern was obtained from http://www.instructables.com