Hi Betsey,
Good for you for wanting to make a difference in the lives of animals! You've been given some fantastic advice so far. I volunteer many hours a week for Safe Haven of Iowa County (www.wesavepets.com), a rescue started just a couple of years ago by a woman in our community who saw that their was a serious need for the animals in our community. It takes a huge amount of time, money, and volunteers to make a rescue successful. Some people that go into rescue with good intentions become hoarders, and that is scary and sad!
I personally could not do rescue work "on my own". I do not have the money to provide proper vet care for several more animals in my life. As an example, last month, Safe Haven ended up having to pay for 2 dogs to get legs amputated. When we got these dogs in, we really didn't think they were going to need such sad and expensive surgery. But they did. One of them would have died a horrible death without the surgery, and the other would have lived with chronic pain for the rest of his life if we didn't do the surgery. I could never have afforded 2 amputation surgeries in one month, and it's a stretch even for our rescue, which gets discounted vet services and has many supporters.
If you don't think you could afford things like that, PLEASE don't even consider trying to "start" a rescue. Look around your area for existing rescues and become one of their committed volunteers, I'm sure they need you, and you will learn a LOT.
THEN, if after a couple of years, you think you have what it takes to start your own rescue, go for it!
Keep us posted!