Draft problems are usually very simple and easily fixed when you understand the facts. The advice below will give you most of the information you need to solve most of your draft issues.

Different beers will like to sit at different pressure. All beers like to sit in static state under a certain "Target" pressure. Each beer will have a slightly different carbonation level and therefore a slightly different "Target" pressure. Generally speaking most beers like to sit in the keg at between 0.8bar (12psi) to 1.0bar (14psi) at 4 degrees C. The issue is that at this pressure, you flow speed might be too fast or too slow. That is why you need to increase or decrease your beer line length and diameter so you can maintain the correct pouring