In general, when I'm making a new form, I start with what factors are important. In this case:
Actor name (or character name)
Mic pack #
Channel #
Next, I consider what the purpose of the form is. Is it the running paperwork for the sound guy? If so, I'd probably make a running list-style form to have at the board. Is it for the backstage crew and will be posted on the wall for "quick glance" access? If so, I might make something more like a chart, possibly color coded.
Then I work through the show in order, plugging in the information as I learn it. Again, depending on what the purpose of the paperwork is, you can then add or subtract info as needed. (Page #, timestamp, notes column, cue for repatching, etc) Once I've done a first draft, it's easy to change it if I don't like the format.
Alternatively, you can take another form you have that serves a similar purpose, and modify it to fit your needs. (A costume plot could be modified to track body mics).