I do a fair amount of applying glaze with a brush and have mixed results. Like you, its because of detail that I can't spray or dip. Though I do use underglazes often and dip in clear.
I think my poor results are due to not having enough glaze. Have to apply more than one and going in a different direction helps.
There are tile makers at our studio that get exquisite results and they use tube liners. They have sets of them with about 20 different glazes. Always having to clean out the tips after each use. They also have much steadier hands than me.
As a student I was taught to dampen the pot slightly before glazing. But here in the damp northwest few do that.
Also, to avoid shelf accidents, I brush things heavier on the upper parts of the piece because I am looking for the blended painterly look but not on the shelves.
Make sure you have a good variety of brushes. GL.