MinnFlyer's approach is the way I do it. I also add a second clunk at the end of the fill line so I can be assured that the tank gets fully drained when I pull suction on the fill line. The clunk on the fill line assures me that the line always sits at the bottom of the tank - especially on installations where I cannot really see the tank that well. When I do not fly a model for a while, I also flush the system with alcohol and drain that, followed by a very - very low pressure air purge from my compressor to dry things up.

Steve