The first thing you need to ask yourself is "Why do you want to play the violin?" Is it something you want to follow closely, or just play for fun? I believe both reasons lead to a rewarding art. If you want to create a career out of it, then I whole-heartedly support you. Doing something you love is one of the greatest things you can aspire to. As for fun, who doesn't like whipping out their instrument at a party and showing off? There's also a "middle" path, where you don't necessarily have to make a job out of your skill, but where practicing and joining competitions and playing in orchestras can be a realistic goal too. If any of these appeal to you, then you're ready to start.
The next question you face is "Are you dedicated enough?" Any instrument takes dedication, but there are I few things I think you should realize: If you take 10 minutes out of your day to practice you will still leap through the levels of skill. I have gotten as far as 2 hours a day, and try to keep myself at an hour a day when I can. Practice is the single most important part of learning to play. You can't avoid it, you can't water it down, and you can't skip it. But that's why we're going to make practice fun, and make it something you look forward to every day.
"What else do I need to put into this?" Besides time, the other investment you must make is money. At first, renting an instrument is cheap, but when you reach higher levels and want something better they can really start to add up. Decent instruments can range from thousands to tens of thousands (some even cost more than 100,000). Add in the cost of strings, rosin, a case (usually free until you get a high level instrument), and (if you buy it separately) a bow, and you're looking at some steep prices. The rig I'm running now probably cost about 4 or 5 thousand. Don't let this deter you; remember, I've played for 8 years, and I want to pursue it. If you have extra 100 bucks laying around, then you'll be fine for a while.
If you have just the slightest interest or shred in the violin (or any instrument), go pick it up. Try it out, ask any questions you might have, see if you can arrange for lessons. Now beginner lessons can be expensive, around 20-30 dollars an hour, but they're very worth it if you want to pick this instrument up. If you believe you have the dedication to practice and keep your violin in good health, then definitely go to your closest music store and pick up a rental and sign up for lessons. You won't regret it.
I'll be releasing more articles weekly or bi-weekly on the subject to help you plan what to do. The next lesson I'll be covering how to hold the violin, and how to hold the bow with a beginner bow hold.
Links: None right now, nothing was really cited, just my experience.
If you have ANY questions, comments, critiques, just comment below and I'll be happy to reply. Thanks for reading!