Military intervention in foreign territories should always be used as a last resort, rather than as a preemptive strike, as there is nothing more costly - not only monetarily, but in the value of human lives - than sending out soldiers to die for causes that usually don't even affect our lives as Americans.
Yes, economic sanctions should always be the first step. Most countries rely very heavily on exports, imports, or both. In most cases, economic sanctions are capable of bringing about the desired result, since they can eventually cripple a nation's economy. We should resort to military involvement only after economic sanctions have been tried and have failed.
There are certain times where economic sanctions are not going to work and it is predicted that they will not work. By not going in with the military we are giving them time to fortify and to get ready for the ensuing involvement. America has the most powerful armed sources in history, if we go in and get them while they are not ready we will win with minimal casualties.
I believe military involvement should always be used as a last resort. In my opinion economic sanctions are not the only option and when they fail that shouldn't signal the need to become involved in a militaristic fashion. We need to focus less on violent tactics and try to find peaceful ways to resolve problems.