Ed--I heartily agree with John--Tamiya Extra Thin. It comes in a tip resistant square bottle like Testor's. It also has the most useful applicator brush I have ever used. Very fine tip which makes it easy to wick into small places.
Since Tamiya has been mentioned, I am also an ardent supporter of Tamiya Masking Tape, the yellow stuff. It comes in various widths and comes off the roll with a sharp edge. I will use the blue painters tape for masking a large area, but around the edges on the color lines, it has to be Tamiya.
Somewhere along the line the folks at Tamiya sat down with real, finicky, rivet counter types like us and asked what do we really need. They have met the need.
Steve Hoxie
Pensacola FL