Soviet textbooks and the Princeton Companion (recommended by others) are likely to be pretty brutal for you. I suggest problem-solving as a better way in. Take

Soviet textbooks and the Princeton Companion (recommended by others) are likely to be pretty brutal for you. I suggest problem-solving as a better way in. Take a look, e.g., at Project Euler (http://www.projecteuler.net/ http://www.projecteuler.net/); find some books aimed at K-12 students doing mathematical contests (there are lots; what's best depends on how much you already know) and online resources aimed at the same audience (e.g., http://amc.maa.org/ http://amc.maa.org/, http://www.mathcomp.leeds.ac.uk/ http://www.mathcomp.leeds.ac.uk/); there are other sources of not-too-routine mathematical problems online, such as http://nrich.maths.org/ http://nrich.maths.org/. This pretty much guarantees that you'll be doing as well as passively absorbing (one of many problems with which is that it's easy to think you're absorbing when actually you're not). There's a very wide range of levels of difficulty. And it's likely to be fun, if mathematics really suits you at all.