The only time I tape is when I am painting downward facing such as where baseboard trim meets the wall. Otherwise I just cut it in. Like others, get a good angled stiff bristled brush. Use a new one or one in good shape where it doesn't have bristles going every which direction. I sometimes clip errant bristles with a fingernail cutter. Unlike what others said, you need to get a good amount of paint on the end of your brush. Why? If you don't, then you have to go over each area several times to get good covering which increased the chances of making a mistake. You need enough paint so that you just go over it once and are done. If you are right handed, work left to right, or up to down. If you are a leftie, work right to left and up to down to give you the best control. I also find that you need to get paint absorbed into all the bristles before doing cutting in. I generally start by painting a non-critical area such as a corner where the color is the same on both walls to get the brush time to absorb the paint. When it has gotten paint absorbed, I then move to the areas where I have to cut in.