Before you start thinking about the steps to getting your girl back, you need to know what kind of break up we're talking about here. Your strategy will be different for different scenarios. If she simply left you for another man, there's a spoke in your wheels much bigger than anything an Internet article can steer you out of.
If she dumped you for cheating, well, it's really simple what you need to do, isn't it, Romeo? You need to make up your mind whether there's one girl for you and if she's the one, and if she is, then you need to convince her of that. That's really it. Just remember that once you've cheated, you will always be dealing with someone who is suspicious and insecure as to your motives. "Transparency" is your friend here. Make it so that you're easy to check up on.
If she dumped you for other reasons, then just get your priorities straight. She might have dumped you over your lifestyle or habits - change them, if she's really worth it. Don't listen to anybody mocking you for being "whipped" if you have to give up a habit to get a girl back; if you have a habit like alcoholism or gambling, then it weakens you as a person, and dropping it to get your love life back on track is as good a reason as any other.
While women will swear that this isn't true, your wealth, status, and success in life do mean something to her. True, she might still love you even if you're a starving artist playing the violin on street corners with the hat out, but seriously, those are the exceptions. Women never go down in status. Once they've had a boyfriend with a car, they're never taking the bus again. Once they find a guy with a house, they want no part of an apartment life. And so on. So if your financial situation is cramping your style, you might want to look into fixing that first.
Now, if the case is reversed and you did the dumping, you're in for a tougher fight than you think. If you're really sure that you want her back and want to pick up where you left off, your job now is to convince her that you're sincere about that. She might not trust you again after the things you said last time. You might have to eat a lot of words.