There are generally four ways to approach the design of katazome stencil - negative (dyed background), positive (dyed foreground), outline (resist lines on a dyed background) and string (dyed lines on a resisted background). Here's a simple design illustrating these four approaches. I've added bridges where necessary so the structure of the stencil holds together.
Oftentimes a single stencil will contain more than one of these approaches.
I am working on a stencil I call "Spring" - some trees with branches and buds. I want to shift the shapes from negative on the bottom to positive on the top. The problem is how to navigate this transition gradually - I don't want an abrupt break. I added a area of grass-like lines in the middle area of the composition. After attaching my cartoon to the surface of the shibugami (stencil paper), I sketched in some lines to clarify where I want to make my cuts. I made black marker lines to represent the positive leaves of grass - these I cut between - and red marker lines to represent the negative leaves of grass. These I cut away.
Here's the middle section after cutting.
It's now ready to reinforce. (See the two "V" bridges at the top edge - these will be cut away.)