I have a big 22 inch metal paint guard that I use when painting baseboard. IT'S A LIFE SAVER! I just run some tape along the carpet that's next to the baseboard (to keep the fibers down) and then use the guard above the baseboard on the wall, to protect the wall while I paint along the baseboard. It saves me tons of time, because I don't have to tape off twice... just once on the carpet.
Where beginners run into trouble is cutting in along ceilings, moldings and other areas that require a perfectly straight line of paint. We'll give you some tips and pointers to help you increase the speed and improve the accuracy of your cutting-in technique.