I would prefer to have a command like branch new. Before i start a new development step, which will become a branch, i usually
  *  open a new checkout
  *  define the branch
  *  update to the newly created branch

So i prevent to checkin something on the main trunk, which shouldn't be there.

Without defining the branch at the development start, i have to remember to give my 'branch' a name and a background color - until first commit.

This working style is inspired by cvs, but i think, it works well with fossil.

Instead of "fossil branch list" i always use the gui, so i don't need this command.

best regards