Cutting and Marking the Pieces
Before you begin cutting out your garment, double-check to be sure all the pieces that you will need are pinned to your fabric. The pattern guide will have an outline drawing of each of the pieces and a list indicating which style uses each piece. Often the layout diagrams list all the pieces used for a particular style.
It's surprising how much time you can save by having really sharp scissors. Bent-handle shears are the best for cutting around your pattern because they allow you to leave the fabric on a flat surface while you cut it out. Keep the fabric as smooth as possible, and cut along the cutting lines of the pattern pieces through both layers of fabric.
If you have altered the pattern, cut from one size's cutting line to another. It is possible to save all the pattern sizes on a pattern by folding the tissue back and cutting only the fabric next to the lines, but it isn't as accurate. With anything except children's clothes, it is probably a waste of effort.
As you cut out your pieces, you will notice notch marks on the pattern. These are triangles drawn along the cutting line. They may be single triangles, pairs, or even three together. On old patterns they may extend beyond the cutting line, but in modern patterns, they are nearly always within the seam allowance.
These represent the points where you must match one piece to another. These notches will be represented on your cutout fabric pieces one way or another. The fastest way to mark them on your fabric is to make a straight cut from the cutting line to the inside tip of the triangle. If you are careful to center your cuts, you can use them to match the pieces exactly.
If you are worried about your fabric fraying, you can cut the notches outside the cutting line as you cut around your piece. Match the shape of the single triangles as closely as possible. Double and triple triangles, on the other hand, can be cut as larger notches. Match only the outside edges of the triangles, and cut straight across between them.
Marking the Pieces
As you cut out your pieces, leave the pattern tissue in place. There is still some information you need to transfer from the pattern to the fabric. If your dress has darts, these need to be marked on the wrong side of your fabric. Look for dots or small circles on the pattern. These indicate locations where things such as ties need to be attached or the location of fasteners.
You should leave the tissue pinned to the fabric until you are ready to sew each piece. This will help you identify the pieces and will keep them from getting mixed up with leftover scraps. Also, as you read the instructions for a particular piece, you might discover something else that needs to be marked.
There are several ways to mark these locations. Dressmaker's carbon and a tracing wheel will leave a dotted line. This is most effective on things like darts. Small dots can be transferred to the fabric with the same carbon and a pencil. If your fabric is folded right sides out, fold your carbon in half so the marking surface is on the outside. Slip the carbon between the layers of cloth removing only as many pins as is necessary. Mark both layers at once. If your fabric is folded wrong side out, fold the carbon the other way, and sandwich the fabric between the layers of the carbon.
If your fabric doesn't take the dressmaker's carbon because of its color or fabric content, you can take a contrasting color of thread and sew through the pattern and both layers of fabric at the marking dots. When you are ready to use the pieces, tear the pattern away from the thread. Cut the thread between the layers of fabric, being careful not to cut the fabric. Leave the threads in the fabric until you've used them to make the darts or whatever they are intended for.
You can also run a pin through the dots, gently tear the pattern away, and mark the pin's location with tailor's chalk. This only works if you've folded your fabric with the wrong sides out, however.