Tack and Tension Tape

how to mask a straight line on baseboards I take my tape I'm going to tack it down set it where I want it and I like to run runs about a foot a foot and a half and I pull it out pull my tape tight and not really tight but kind of taut and that way I can move it back and forth and line it up exactly where I want I like my tape about a 16th of an inch onto the baseboards that way if you step away from the wall your line looks