I think economic sanctions are effective in achieving foreign policy goals. Economic sanctions can cause a nation's economy to suffer and therefore force a nation to change their foreign policy to remove the economic sanctions. Economic sanctions are useful for preventing nuclear proliferation in countries such as Iran or other Middle Eastern countries.
Sanctions can be very effective to achieve foreign policy goals. I think they can also cause a lot of problems and animosity between countries if they are misused. For me, sanctions are a toss-up. One day I am against them, the next I hear the idea pitched and I am for them.
Economic sanctions are sometimes, but not always, effective in achieving foreign policy goals. Every country needs a running economy to function, every military needs funding. If sanctions are harsh enough to severely impact a nation's economy, said nation would think twice about what it was doing lest its economy suffer. But, sometimes foreign sanctions are not enough. In such situations war may be the only solution, however undesirable war is.
In the past, economic sanctions have not been effective in their main goals. If we look to Iran, placing the sanctions did not affect the government enough to cause any drastic movements. Even more recently, we can see how larger countries like Russia do not feel sanctions as a threat. Many countries threatened to pose sanctions on Russia after their involvement in Ukraine, but Russia continued with their involvement because the sanctions would not be that effective.
Plus, the idea of placing sanctions is not good for foreign policy goals. Most countries do not bend under the pressure and most of the countries do not receive what they want when making deals to lift sanctions.
Sanctions can be effective in some situations, but they aren't the most effective means of achieving goals and can also be used to create a bias against countries. When sanctions are in place it encourages the one being sanctioned to seek resources elsewhere. Often this comes from nations that are against the nation placing the sanctions.