Here are the crucial steps to take for that smooth straight- line even in the center of a painting area:
1: For measure make use of a ruler or tape measure and then start from the floor, mark the desired height with a light pencil mark (for a vertical line, use a corner as the initial point). Repeat the same process for the other end of the line also.
2: Secondly, slowly take off a portion of the painters tape and start at the first mark and pull the tape up-to the second mark. Make sure not to bend/bow the tape in order to keep the line straight.
3: Seal before painting with the contrasting color, gently brush the edge of the painter’s tape with the base wall color on the side where the contrasting color will be painted. Do not cover the full-width of the painter’s tape. This will fully seal in the tape for a clean line later and then allow to dry.
4: Use a paint brush/roller to paint the wall with your new trend or contrast color. Cover the entire surface and once it is completed, peel off the tape while the paint is still wet. The end result should be a neat and clean, straight line between contrasting colors.