You want to make your way to the point where you can write a proof and check it without needing feedback telling you where it falls down.
In addition to that, you've got the basic undergrad math major curriculum.
Maybe look at http://web.evanchen.cc/napkin.html as some sort of goal, to understand everything you find interesting there, and a small set of medium to hard problems that you could use to track your progression. (It goes quick so I'm suggesting it as an example plot of a subset of a curriculum, not necessarily a great learning resource. It's clearly aimed toward a particular sort of reader, and it is a bit tilted towards parlor trick mathematics. It's kind of a neat document if you finished a math major a decade ago. Edit: this link is weak on analysis.)
Oh, this is definitely an answer you should read critically.
You want to make your way to the point where you can write a proof and check it without needing feedback telling you where it falls down.
In addition to that, you've got the basic undergrad math major curriculum.
Maybe look at http://web.evanchen.cc/napkin.html as some sort of goal, to understand everything you find interesting there, and a small set of medium to hard problems that you could use to track your progression. (It goes quick so I'm suggesting it as an example plot of a subset of a curriculum, not necessarily a great learning resource. It's clearly aimed toward a particular sort of reader, and it is a bit tilted towards parlor trick mathematics. It's kind of a neat document if you finished a math major a decade ago. Edit: this link is weak on analysis.)
Oh, this is definitely an answer you should read critically.