#1 Most Important Thing:
A good webcam. Logitech c910 and c920 are considered to be the best of the best. Do not start until you have invested in one of these.
Streamate is heralded as a great place to start camming because of the high traffic if you don't geoblock. Never used it myself, but I think they have some highly enforced rules that will help a newbie, like no offsite communication, no skype, no free chat cumshows, stuff like that.
MyFreeCams can be really difficult for models who are starting out because of the camscore. The higher it is, the closer to the top of the page you'll get. If it's too low you risk little to no traffic. However, this is the site where I started out and it's worked out great for me. If you want to be an MFC model, just do as much research as you can about this site in particular.
Regarding payouts, it depends on the site. MFC is every 1st and 16th of the month, I think Streamate is once a week? Some sites require you to make a minimum before you get paid. As to how much money you'll make? That is a mystery until you try. Most girls do not make a whole lot the first few months of camming. Some work hard to get to the top, others get really lucky. It's definitely not a get rich quick scheme or "easy money" all of the time.
Good luck if you start!