The best thing to do early on, in my opinion, is to look up local adoption agencies and ask for their information packets. Look through your local yellow pages, or the online yellow pages of the largest city in your area, and call up agencies. Ask them about the programs they offer, about timelines, and for their information packets on certain programs. Some will be willing to answer questions pre- receiving the packet, some won't. That's okay.
Whatever you hear from each agency, write down. As a warning, some will give you wildly optimistic information. You'll figure out what's "optimistic" [misleading, actually] by comparing information from several agencies as well as agency information online. If you find a place that tells you something too good to be true? Run, don't walk, in the other direction.
There are local agencies and there are national agencies (like Holt International, for example). All agencies tend to have different programs, different strengths, and even (in some cases) different qualifications to adopt. It takes a fair amount of sorting through information to get an understanding of your options.
Once you have an idea of the programs available to you, and which ones you might pursue, call the agencies back and ask for someone to talk to with your questions. Go over your concerns about the program, the timelines, the qualifications, the costs, the outcomes, the support given pre- and post-adoption by the agency, etc.