Today I made this small ditty bag and thought I'd share some tips you might find useful. These tips are geared toward the small size because it is the most challenging to sew, but the tips could apply to all sizes.
Don't Skip Steps
You might be tempted to skip some of the steps in the pattern (like basting), but you'll get better results if you take the time to do them all.
Recommendations in the Pattern
There are two things pointed out in the pattern, but let me highlight them here in case you missed them:
1. Apply interfacing to the (2) focus fabric A pieces only (not all four A pieces).
2. Use the uncovered ends option.
True Your Pieces
Between cutting & interfacing the pieces can end up slightly different sizes. Making sure they are all the same size will help.
Darts
Make sure your darts are pretty much all the same height & width. It is hard to make them perfect, but just make sure there are no glaring differences--especially on the focus fabric pieces. The darts on the lining pieces won't be visible, so don't worry about those too much.
When you sew the second set of focus fabric pieces to the zipper, make sure the darts on both sides of the bag line up pretty well.
Centering
Pay a little extra attention to making sure everything is centered (loop, zipper ends, etc.). I have one bag where the zipper is at a slight diagonal because I wasn't paying attention. Whoops!
Hand Baste Zipper
Instead of pinning the pieces to the zipper, try hand basting them to the zipper. Then you won't have the pesky pins to deal with during sewing.
If you've sewn zippers before, you probably noticed the lining pieces & focus fabric pieces on each side are sewn to the zipper in individual steps. It is fine to sew them both to the zipper in one step for each side, but I find it easier to keep everything matched up by sewing them individually. If you hand baste the pieces to the zipper well, combining these steps is ok.
Cup the Pieces
The pieces aren't going to lay flat because of the darts, and will naturally form into a cup shape. When you sew the zipper on you are sewing through the dip, rather than trying to go over a hill. I hope that makes sense.
Massage those Seams
Really massage those seams out once you are done. Pressing around the outside edges first will warm up the fabric and make it more pliable. If there are little points sticking out here and there around the edges, use your fingernail to press them back into the seam.
Shape with Iron
Once you are done, stuff the ditty with a clean plastic bag and close the zipper. Press the top and sides to get rid of any wrinkles and shape it up nicely. Be careful to avoid pressing the zipper. Leave it in place to cool and set.