1.) Cut out the fabric pieces.
Place the center front side of your corset pattern against the fold, and pin it to the fabric. If you have fabric weights, by all means use those instead.
Using a pencil, chalk, or some other non-permanent material, trace the outline of the corset pattern on the fabric. Cut around the pattern tracing, leaving 1/2 an inch of seam allowance along the bottom waist. Around the rest of the pattern, leave no seam allowance--cut the cloth right along the edge of the pattern. If you're making a corset with straps, leave a 1/2-inch of extra fabric at the ends of the straps as well as along the bottom.
Do all of the above to the lining fabric you're using. When both pieces are cut out, lay them one on top of the other and compare; trim away any small differences between the two pieces.
2.) Make the tabs for the corset
Lay the tab pattern on the same cloth you used for the corset. If the outer and inner material is the same, you'll be cutting out 16 pieces from the cloth; if you're using a different material for the lining and the outside cloth, you'll want to cut out 8 pieces from each kind of cloth.
For tabs with satin edging:
Cut out the tab pieces you need (as specified above), cutting right on the edge of the cardboard pattern and leaving 1/2 an inch of extra fabric along the top and no excess seam allowance along the sides or bottom. Match two tabs together, one of the lini ng material and one of the outside material, right sides out.
Starting at one top corner, lay the satin ribbon wrong side up against the right side of the outside fabric. Matching the ribbon and fabric edges, sew a seam 3/8 of an inch away from the edge along the side, bottom, and up the other side of the tab. Cut the end of the ribbon even with the top of the tab, which should now resemble a kind of pocket with the top open.
Turn the satin ribbon over the raw edges of the tab and hand-stitch it down on the back of the tab. Once you've finished all the tabs, iron them (if the corset fabric permits it) to get the satin edging flattened out.
Tabs without satin edging
Match pieces of the lining and outside material together, wrong sides out. Starting at the top corner, sew a seam down the side, across the bottom, and up the other side of the tab, 1/2 an inch away from the edge.
Trim the extra seam allowance close to the seam, especially around the corners, and turn the tab inside out so that the edges are finished. Iron it as flat as you can.
Lay the outside fabric of the corset flat, with the side you want showing face up. Starting one inch in from the back center on either side, lay the tabs, right side down, along the bottom edge of the corset. They should be upside down, so that the raw tops of the tabs are even with the raw edge of the fabric.
Lay four tabs on either side. The tops of the tabs should be as close to eachother as possible, with the wider bottoms overlapping slightly. Now lay the lining fabric on top, with the side you want against your body facing down.
Pin the bejeezus out of the bottom edge, making sure that the outer fabric, tabs, and inner fabric are all smooth and even with eachother.
Sew a seam 1/2 an inch away from the edge all along the waist edge of the corset, stitching the tabs and the two layers of corset fabric together.
Trim the excess close to the seam, and turn the pieces right side out. Iron things flat. Baste the two layers together with a seam running up the back centers of the corset, from the waist to the top, 1/4 an inch away from the edge.
4.)Mark and sew the channels for the boning and the busk
Sew along the marks to create channels for the boning. Straight pins are useful for insuring that both layers lie flat and even. Sew from the top of the corset to the waistline on all stitching, or from the waistline to the top--this avoids wrinkling and twisting the fabric. Test the first channel to see that it is indeed wide enough for the boning before doing the rest.
If your corset has straps, now is the time to connect them together. Sew the outer layer's front and back straps together half an inch fron the end of the fabric. Now sew the inner layer's straps together with the seam 1/2 an inch from the ends of the straps, like the outer layer. Sew them so that the finished side faces the inside on the inside layer, and faces the outside on the outside layer.
If your corset has straps, do the same for the armholes. Fold the ends of the ribbon in so that they don't show.
Slip the busk into place, and poke two holes in the fabric to match the holes in the busk. you can sew a buttonhole stitch around the holes, making sure not to sew the two layers together. Once the busk is in place, a ribbon will go through the holes in the lining and through the busk, and tie together in a bow on the front of the corset to keep the busk from sliding out of place.
Following the instructions for your grommets, insert and pound the grommets into place. If you've never put grommets into an outfit before, I highly recommend practising on a piece of cloth before you do the corset.
If you're not using grommets, cut a very small hole in the fabric, and sew a buttonhole stitch around it. You can also sew a buttonhole stitch around the metal grommets, to make your outfit look more period.
It is helpful to finish off the lace you're going to use to lace your corset with by rolling the ends small and either wrapping clear tape or thread tightly around them, or dipping them in wax. This makes it a LOT easier to lace with, and reduces curses and mumbles behind your back.
9.) Immediately rush to the nearest mirror