You'll need to mark your fabric to note specific points. You'll want to make sure that any marks you make are either in the seam allowance or capable of being washed or brushed away. You don't want to ruin your garment with marks.
Chalk – This comes in various forms. Nice method to avoid fabric staining.
Marking Pencil – Marks brush or wash out.
Water Soluble Pens – Marks come out when item is washed.
Tracing Wheel & Paper
Marking straight lines can be done easily with a tracing wheel and tracing paper. Place the paper under the fabric and use the wheel to transfer lines.
Tracing Wheel – Tool with handle attached to a circular wheel. The wheel can be smooth or serrated. It is used to transfer markings from a pattern to fabric.
Tracing Paper – This paper lies between the pattern and fabric. When you run over it with the tracing wheel, the material on the paper will transfer to the fabric. The tracing marks will wash away with water. The paper may be coated in wax, chalk or other material and it comes in many different colors.