I guess it’s just practice. My problem is staking out the time and being patient - which means, in the first place, choosing whether this one, of so many other ideas, is something I really want to spend time on.
By the way, the cookie site I posted shows a lot of techniques, simple to advanced. She also has tutorials on airbrushing - and look how she makes a burlap-looking pattern:
http://www.sweetsugarbelle.com/2015/03/easy-decorated-burlap-cookies/
I don’t think any of this stuff is terribly difficult; but you have to “commit” ;-)
There used to be a lady in our circle who made beautiful cookies with hand-painted Santa Claus faces, really works of art. But that was her trademark, the only ‘fancy’ thing she did for Christmas; so she got very good at it and well-known for it. Everybody looked forward to those cookies each year.