Try a plunger: If it's a double sink, use a wet rag or rubber stopper to block the other drain. Place the plunger directly over the drain until it forms an air-tight seal. If you have trouble forming an air-tight seal with the plunger, run it under some hot water to make it more flexible. Move the plunger up and down to dislodge the clog from the drain.
Most plumbers, pipefitters, and steamfitters learn their trade through a 4- or 5-year apprenticeship. Apprentices typically receive 2,000 hours of paid on-the-job training, as well as some classroom instruction, each year. In the classroom, apprentices learn safety, local plumbing codes and regulations, and blueprint reading. They also study mathematics, applied physics, and chemistry. Apprenticeship programs are offered by unions and businesses. Although most workers enter apprenticeships directly, some start out as helpers. The Home Builders Institute offers a pre-apprenticeship training program in plumbing and other trades.