How to start with mathematics? I fell in love with mathematics a bit too late when I've already taken decisions regarding my future, career-wise. Now I would like to learn math on my own but I'm a bit confused as where to start. My knowledge of mathematics is comparable to that of a 15-16 year old highschool freshman. I would like to know how would you (if you were in my position) start your learning adventure on your own. There are a lot of resources online, of that I'm sure but I would like to follow a path. I'm pretty sure I can learn mathematics on my own and been thinking about this decision for almost a year. 

Thank you!
I'm also an older person trying to teach myself math. I took math till high school and since then I have taught myself to beginning-graduate level in one area (analysis) and bits and pieces of other areas at an undergraduate level. My suggestions,


Time is limited, don't waste it on popular books. Study high-school and undergraduate textbooks and do the problems.  It may be a good idea to     go to an older generation of textbooks since they are less chatty than the current ones.      The Chicago Undergradute Mathematics Bibliography is useful. But don't obsess too much on which book to read. At this level it is hard to get things very wrong. Pick one book and persevere with it.
Work in sprints. It takes    time to get into a
productive frame    of mind. So trying to do
math for a little    while each day
does not lead to any    progress and
results in frustration.    Instead,   dedicate
a week of your vacation or at least a 
whole weekend for learning something 
new. Between these sprints revise what you have learned by doing more problems.
Get it right the first time. While studying a text if you feel that you don't understand something fully, stop and work on your difficulty. Look at other books. Ask for help on forums like this. Go and brush up on the prerequisites if need be. But never leave a gap. Don't skip more than one exercise in ten.
Be    patient. A good undergraduate     training takes 4 years of     work with teachers and peers. My      guess is it will take at least a      dozen years to achieve the same level   of mathematical maturity working      part-time on your own. But at the end your understanding will be better than an undergraduate's since you will have had the benefit of greater intellectual maturity and more time to reflect.
Is it worth it? Math is no doubt beautiful. But the time you give to it comes at the cost of your career, personal life and other interests. Are you willing to make the necessary sacrifices? If you are then it might be a good idea to make the sacrifices upfront and go back to school to learn math. The chances of fulfillment would be much higher.
Before starting Basic Arithmetic(Pre-Arithmetic) study the definition of mathematics/Its history/influential scientists/mathematicians in it. Then the branches of mathematics and their definitions and then learn the number system and mathematical skills and number skills and think deeply about it like why it is based on ten digit then go on learning Arithmetic(all the operations and their definitions) Practice it Master it completely then memorize and mesmerize(Think every time about what your memorizing) all the arithmetical tables(Addition tables, subtraction tables, Multiplication tables) which will help you for mental calculations and remember always visualize numbers.
Then when your Mental Calculation is awesome!!! then move on to PreAlgebra master it then Algebra master it and then modular arithmetic which will give you nice understanding of how mathematics work then Geo , Trig , Calc all other things then study their relations do extensive word problems and numericals master them then do research on them. Take part in IMO , discover your own theorems. Solve a millionaire problems . take part in mathematical discussions and study science.