The Summer Gore Skirt has straight seams for each of the gore panels. Although the directions call for a lining, depending on the fabric that you chose, you may not need to line it. If you do line it, you may want to use rayon or silk for the lining if you plan on wearing hose or tights with it. Otherwise cotton or no lining is fine. If the skirt will be wash and wear, I recommend finishing the seams even if it is lined.
Without a serger, you could finish the seam with a zig-zag stitch, triple zig-zag, or a French seam if the fabric is not too heavy. You may need to try a few different ways to see what works best with your choice of fabric.
I have a foot that keeps the thread from pulling the end of the fabric, which is pretty handy for over edge seam finishing.
Sewing French seams leaves a very clean finish on the inside of the garment. 1) With wrong sides together sew a 3/8" seam. 2) Trim half of the seam allowance to 3/16". This may seem difficult, but with a little patience and practice, it is pretty easy to cut away half of the seam allowance.
3) Press the seam open.
4) Turn the fabric right sides together and press the seam closed.
5) Stitch the seam at 1/4".
Finished inside of garment with French seams (pressed and ready to topstitch).