Being conservative on a bike is a good thing, but you need more than just the proper mental attitude - you need the experience to react immediately and properly in an emergency. If you think about what you need to do, it will be too late.
I've been riding for more than 25 years, and have put more than 250,000 miles on motorcycles. You've gotten some good advice here, but I'll add some more from my experience. Take a Motorcycle Safety Foundation riders course before you even buy a bike. You'll learn more than you think you could in a few days.
Don't start out on a Gold Wing or a Moto Guzzi. You don't have the experience to handle a bike that large. There will come a time when you hesitate a fraction of a second, and the extra mass of a large bike will send you over the edge and onto the pavement. Get something smaller, such as a Suzuki GS500E to start with.
Do not emulate the idiots who ride around wearing beanie helmets, chaps, and t-shirts. Your protective gear is the only think keeping your flesh from coming into direct contact with asphalt. Buy a Snell approved full-face helmet, a leather jacket and leather pants, and riding boots that not only cover your ankles but provide enough lateral support that you cannnot bend the boot tops left and right. This will keep your ankles from shattering in an accident. Chaps are useless if you go down. Think about it. Chaps don't cover your butt, which is the most lkely portion of your lower body to slide along the pavement. Make sure you leather pants and jacket have adequate armour, including a back protector. The full-face helmet (I have an HJC) will protect your face when you go down, as well as keeping the wind, bugs, and rocks out of your eyes as you drive.
As mentioned above, wear bright clothing. You do not want to blend in with the traffic. My motorcycle is yellow, as is my helmet, and I have a yellow/black/white Vanson jacket.
Whatever you buy, after you've taken the MSF course, sign up for a motorcycle school. Reg Pridmore's (http://www.classrides.com
) school is excellent for beginning riders and travels to various locales around the United States. Don't bother with Keith Code's school or his books. He teaches some good stuff, but he also teaches too much dangerous stuff for me to recommend his schools to beginners.