How many mistakes is it possible to make in one sewing session?

Quite a few judging by the number made between us at the social sewing session on 6 December.  Here are some of them so you can remember to avoid them in your sewing.
1. Putting pins in the wrong place for machining the seam.  By this I mean not thinking about on which side of the fabric and in which direction you will be sewing the seam when you are putting your pins in. Thus you find that the pins are either (or both)  on the underside as you sew or not pointing in the right direction for easy removal before the the presser foot arrives at that spot.

2.  The iron not being hot enough for fusing fusible interfacing to the fabric.  Remember always to do a test first on a piece of spare fabric with a scrap of interfacing.  This way you can find out how hot your iron needs to be.. Always press, not use an ironing motion, and you must make sure that your fabric and interfacing are perfectly smooth and flat before you start or you could create permanent wrinkles in your garment .  Once fused then leave the piece to cool before picking it up and using it.

3. Forgetting that you should add a seam allowance before cutting out your fabric.  Some patterns, such as Burda magazine patterns or patterns that you have drafted to your own measurements, need seam allowances adding to them before the pattern is is used to cut out the fabric- Don't forget to add them! 

4. Not sewing in the right direction on a seam when you are matching up a fabric pattern, such as stripes, checks etc.  Always machine away from the point where you have matched the design otherwise your fabric might slip and no longer match when it reaches that point.  Consider tacking (basting) rather than pinning and/or using a walking presser foot on your machine if you have one.

5.  Finding that you cannot hand crank your sewing machine.  I'm not sure that this is valid for all machines but one sewer was trying to lower the needle by turning the handle of the machine by hand but it would not work.  She found it would not lower the needle when the bobbin winder spindle was pushed to the right to wind the bobbin.

6.  Sewing with no upper or lower thread.  Don't forget to check that your needle is threaded and your bobbin has not run out, or about to do so, before starting to sew again after a pause.

7.  Stitching down darts or seams without checking that they are lying the right way.  Pattern instructions usually tell you which direction  to press darts or seams once you have sewn them.  Make sure that when you come to stitch across them, for example when applying a waistband to a skirt, that they will be sewn in the correct position and not the wrong way around.

8.  Sewing in a zip with the zip slider pointing down instead of up.  When sewing in zips by certain methods you can get around the difficult bit of sewing by the head of the zip by moving the head of the zip past the needle- see the previous post for an example.  However you can only do this if you can grab the the zip slider which is easier to do if the zip slider is pointing towards the top of the zip.

9.Not concentrating all the time.  Be warned, don't think that, just because you have managed to do a difficult bit of machining successfully, you can relax.  That's when your lovely straight line starts to wobble.

10.  Getting the wrong bit of cloth caught into your stitching.  Always make sure that you are only stitching together what you intend to.  It's easy to catch up some fabric unintentionally, especially when dealing with gathered fabric or curved stitching.

11.  Sewing with a zipper foot in the wrong position.  Zipper feet are designed to enable you to stitch as close to the zip teeth as possible.  In order to do this, depending on the design of your machine, you need to move either the needle or the zipper foot to the correct position  in relation to the side of the zip you are going to stitch.  If you don't then you could find yourself either sewing on the teeth of the zip or too far away from the teeth.

I'm trying to think if there is anything I have sewn without making a mistake at all and I can't think of one.  What is your most frequent or your worst mistake and how did you deal with it?