Dear Janes,
I use self fabric, because my belt loops are usually on tailored trousers. Cut a strip on the lengthwise grain of your fabric long enough to make all the belt loops for your project. The width should be four times the finished width desired. Press the strip in half lengthwise. Open out the strip, and press one side to the center, using the first (center) pressing as a guide. Press the remaining side to the center as well. Then press in half again. The loops will now be the finished width. Stitch both sides of the strip. Cut the strip in segments for each belt loop, remembering to leave seam allowances and ease for the intended belt.
Since I make lots of pants, and trained students to do it in the lease amount of time for expediency, I use this method to sew them to the waistband. Pin the raw edge of the belt loop to the waist of the garment where desired. Sew the outside seam of the waistband to the garment. The first side of the belt loops are sewn in place. Set your machine to do zigzag, and sew the second side of the belt loop just past the fold of the waistband, going back and forth over the raw edge of the belt loop. Then sew the second side of the waistband in place. Professional belt loops in no time at all.
There's no such thing as a dumb question, unless it's the one not asked.....
Teri