Ok. First things first. What kind of music do you like and want to learn to play? If James Taylor is an inspiration, an acoustic guitar is right for you. If slash is more your speed, an electric guitar is a better choice.
Buy a guitar! If you live near a reputable music store, I suggest you go in and feel for the instruments that are available to you. Although all guitars look good on hanging on their wall, some are easier to play than others and better suited for the beginner. Salespeople will advise you on your options and help you choose the right manufacturer and model.
Choose a lesson format. There are so many ways to learn other than expensive private lessons. A simple online search will return various options, including books, DVDs, CD-ROMs and online video lessons. I suggest that the format you choose, you choose that there is a comprehensive support system that is connected to the product. Forums, bulletin boards, etc. can help answer questions, give feedback and make you feel part of a community.
4. As adults, family, work and social responsibilities learn to play challenging. Even if the DIY approach is convenient, you still need to spend time every day or every week to sit down and play. To stay motivated, start with simple guitar songs you already enjoy listening to.
Too many novice guitarists quit because they get frustrated or bored with their lessons. This did not happen to you.