Many stitchers could stitch Scotch Stitches better if they know two things, and both have to do with thread tension. These two techniques may also be used for Cashmere Stitches and Pavilion Stitches, basically any stitches that have short stitches and long stitches.
Both issues can be seen in this example. The first issue involves that short stitch - it really needs to be plump or else it will be buried by the stitch next to it. This is due to too much tension placed on the (typically) first stitch executed in the Scotch Stitch, though I have pointed out the first stitch on the right and the last stitch pointed out on the left.
To solve this problem, ease up on the tension for that diagonal stitch over one canvas thread. This should leave that small stitch plumper.
The second issue is that the middle stitch wants to lift up higher than all the other stitches, basically because it is longer and the tension is just not maintained well.
The picture below shows one stitch in the upper right hand corner that pulled up, while the other three are not raised. You may find that placing a tacking stitch just before stitching the longest stitch will solve this problem.
The tacking stitch is underneath the Scotch Stitch and therefore hidden. Remember the thread type may mean that you can not use this technique, only those threads that will lay low enough to be hidden when stitched over will work.
Here is a stitch diagram of a typical Scotch Stitch:
These two stitch diagrams show where to place the tacking stitch during the execution of the Scotch Stitch:
Next time you see these two issues with your Scotch, Cashmere or Pavilion Stitch, try one or both of these tips.