Typically it is a good idea to have the following requirements to go to a good school in US:
1. GMAT test and a good score.
2. 3 years of full time experience in US.
3. Interest in any of specialisations in MBA as in the previous blog.
If you are already in US, working for a company, you can try to convince your company to pay for it. Typically, they will say you pay for your tuition and get it reimbursed after you get 'B' or better grade. I know one of my friends, he was in technolgy field for about 6 years, then he started getting involved in finance deparment. He finished his MBA through his company and he is the finance director there now.
If you are not in US, there are more steps that has to be taken -- like the visa process, choosing the universities, writing the Statement Of Purpose and so. For this, please refer to my good friend Raghu's blog: here.
In all this the caution is, when the economy is good, its relatively easy to get job and very good salary. But, when the economy is bad, like these days, ite really really tough to get a job in MBA than in technical field. You should be ready to face both the sides. In this economy, you need hard work, patience and better time management to land a job.