What is the best instrument to paint a horizontal panel paling? To avoid paint running into the next door neighbours side? Also how...

To avoid paint running into the next door neighbours side?

Also how should the top and posts be divided?

One side is brown the other side green
Answers:    Did mine second summer - very darkened brown and other side was insubstantial. Had to do it with a brush.
You entail to know who ownes the fence first. The support posts are usually on the side of the being who owns the fence. If you own the barricade I suggest you paint [with a brush- a sprayer will go through the slats and affect your neighbours plants] your side and the top and underside of respectively slat, plus the 3 visible sides of the support post and top of it too. [ Then possibly your neighbour will paint his side green also. ]However , if the balustrade is not yours. You should only paint the sides of the slats facing your garden. Having said that it won't look discouraging, as the rest will look as if it is shade and light anyway. I personnally muse all fence should be green as it melts into the situation and is not so obvious as that hideous orangey brown citizens seem to paint them. AND green shows bad your plants better too.