strait tape lines & caulking?

Something that helps is to be on a good step ladder close to your work. Limit the coffee, take short breaks, and keep the brush base clean.

For freehanding:
-Lock your wrist, and paint with your shoulder or elbow(whichever is in better shape lol) in a twisting motion.
-Load you brush, and put on a thich ridge of paint 1/2 inch away from your line.
-Use that "resevoir" to siphon paint to the applying edge of the brush, usually near the center of the brush not the end.
This edge will consist of a bundle of 4-10 hairs which reinforce each other.
-The size of the brush sometimes doesn't matter. A 3" holds more paint than a 2" and be faster depending on the job/area. For me, a very small brush shows my shaky hand, and I get tired of dipping.
-Don't push hard. Spread it with 4-8in strokes with a slight curve at the begining and the end.
-If you get a blob of paint, get rid of the paint in the brush elsewhere, and brush underneath it to deflate it.
-If paint gets on the trim, wipe off and redo later.
-First, smooth and/or fill in the the edge before, for a clean line. Knock off the high spots with 60-220 grit wrapped around a paint stick, and smooth it out with caulk(flexing problem areas) or spackle(I prefer). Let dry to shrink, and touch up if necessary. I wipe spackle briefly with a wet cloth.