Slide the long flat metal edge of the paint shield into the corner between the trim and the carpet.
Press the paint shield downward, into the carpet fibers. Your goal is to push back the fibers, leaving only the trim exposed for easy painting. The paint shield should be firmly jammed into the base of the trim, providing a tight seal between the trim and the paint shield.
Paint the trim using fast-drying latex paint and a foam brush. Foam brushes provide thinner coats of coverage, less likely to drip as you paint, further protecting the carpet from accidental paint splotches. Thin coats also dry faster than thick coats.
Remove the paint shield after the paint dries.