I have a favorite pants pattern. It is an elastic waist pull-on pant that makes up beautifully in linen. The only problem: they have not pocket. So, 
I added one!
I traced my hand so I would know about how wide I needed it to be.
I drew a slanted tear drop around my hand.
I added 5/8 inch seam allowances around it.
I taped the pocket to my pattern tissue, matching the side seam lines and cut out my pants. (You should note that this took about an extra 1/2 yard and had much wasted fabric.)
I stitched a piece of ribbon along the seam allowances on the front of each pocket for 
support. (At this point I referred to a handy sewing guide. Look for a review of the Reader’s Digest New Complete Guide to Sewing coming soon.)
I basted the pocket opening closed along the seam allowance.
I stitched the pants leg together from the hem up to the waist, following the curve of the pocket.
I clipped the corners at the pockets and finished the raw edges. I removed the basting and “bingo!” I’ve got pockets!
