I believe that all the above answers are quite splendiferous. (I do not use that adjective lightly. :)) I'd like to provide my own input, though it might be slightly Socratic:
What do you care about? Ask yourself this and answer honestly. Does mathematics happen to be one of the things you care about? Or do you find mathematics to be a torturous beast that has no soul? Hyperbole aside, this matters.
It is very easy to be good at math even if you don't care about it. That applies to all subjects, really. Nearly anyone can sit down, go over a text, and learn the associated processes and patterns of it. But, here is my point: It is so much easier if you care about it.
I can't convince you to do this; it is your own task. But let me clarify that caring about an exam grade or your math grades does not necessarily mean you care about math itself. To care about math involves doing things that most people think are crazy or odd. For example, I spend my spare time doing mathematics and felt literally sad when I learned that $\int x^x dx$ cannot be expressed in terms of elementary functions. Do you have this same amount of interest in mathematics? Note that I'm not saying you have to be like this, I'm just saying that it helps immensely to actually care about what you're learning.
Now, I would not say I am near the caliber of the majority of the users here, but this is what I have learned about learning math so far:
- Be patient. You can't learn everything at once. Even Goethe, one of the smartest humans to live, was aware of this fact. (He made a play, Faust, that expresses this fact.) I like to take pointers from people like him.
- Don't lose hope or give up early. I've realized that it's not my intelligence that causes me to be decent (I don't really think I can call myself "good") at mathematics, but rather my perseverance. I literally spent two weeks trying to solve one problem and I failed. But the point isn't that I failed: It's that I tried until I could do no more. I exhausted every thing I could think of and then acknowledged that this problem was simply beyond my current understanding. I like Edison's quote along these lines: "I have not failed. I've just found 10,000 ways that won't work."
- Learn at your own pace. I can't emphasize this enough. I had a really interesting experience a few months ago with a friend. I was showing him how to solve quadratic equations. I tried to show him how to use a general approach and see the inherent process behind why a particular method works. This failed miserably. But, I did learn something: This was beyond his pace. So, instead of using this method, I illustrated it with concrete numbers. Then, I showed him how the general method is underlying these numbers. He had a lot of trouble with the general idea, but he did eventually solve it. Let me tell you, though: This wasn't a stupid person, by any means. He just hadn't learned this yet.
- Don't take your grades too seriously. One of my favorite people in the world and one of my greatest teachers told me this, "It's just a number. You can't reduce a person to a number." This is one of the wisest pieces of advice I have ever heard. But be careful: My teacher here was not saying that grades are irrelevant, he was saying that your grades should not be the Gospel. They shouldn't be definitive concrete that roots you to a particular level. Too many people fall victim to this. I see it everyday, sadly.
Now, let me try my best to give you some specific and exact advice:
- Pinpoint precisely why you fail. I'm not saying you are a failure, or anything to that extent. I'm saying that you, as a human (like us all), fail to some extent. Everyone fails somewhere. What's important is figuring out where, exactly, that you are failing. You cannot fix a problem without knowing what it is. For example, I struggle with English and particularly grammar. It pains me. But, once I realized where I was failing, I did a lot better. I realized, "Wow... My understanding is so elementary and inaccurate that it's no wonder I can't understand what a prepositional phrase is." I realized that, the very base of my understanding was horrible and inaccurate. I also noticed that I was failing because I was trying to put out a fire with an ice cube. My method of learning grammar was inherently lacking: I tried to understand the concepts of grammar based solely on their definitions and how they function, rather than trying to understand them intuitively and inherently by analyzing them in specific sentences. I learned that, to my surprise, a word's function and classification depends entirely on its use in a sentence.
- I looked over a few of your questions and I think your issue is that you've skipped into waters too deep without any way of floating. That is to say, I think your class(es?) have went beyond your mathematical understanding. They are not at a comfortable level. Don't be embarrassed or upset over this: You can fix this. It has already been suggested, but I'd really recommend khanacademy. I recommend taking a week or as long as you need to work past the elementary exercises involving addition, subtraction, division, etc. It is best to do an exercise until you get a streak, which usually tells you to move on. I personally would not focus on the word problems, but that is a choice of preference. If you need help with any of the exercises, there are up to three videos explaining the concept. I find Sal to be impressively great at illustrating complex ideas. (It may help to learn about the concepts you're covering in class by using khanacademy while you work your way up to those concepts as a side project. That may complicate things, but it should help.)
- Consult Wikipedia profusely. This is something that has helped me greatly in some of the most bizarre ways: I learned about Louville's proof involving the thing about integrals like $\int x^x dx$. Now, I in no way am at that level of mathematics to fully understand what Louville was doing, but I get the point he made. (There's a subtle difference between those two: If you fully understand, you can reproduce the result yourself. If you get the point, you can use the result to your advantage literally or as a supplement to how you view other concepts.) P.S. Don't be surprised if Wikipedia makes you feel stupid. It does this to me all the time. There is a profuse learning curve to the mathematics on that site, but you can get bits here and there that make a significant impact on how you understand things. Even one sentence can enlighten you a lot sometimes.
I have wrote you a book that could be even longer (I apologize if I am in any way verbose, but I have written this all in my best attempt to help), but I'd like to end on one final point:
- Participate in the lovely community here. I've been using this site for a few days now and I find that it's one of the most interesting ways to learn about mathematics. Helping other users here is also a great way of enhancing your own understanding. Be careful, however. Do not try to answer a question unless you feel comfortable with what you are submitting. That is, you would put this confidently on an exam if the question came up in school. At the same time, try not to strain the denizens here with too many questions. Try to give as much as you take. Now, I have a feeling this is difficult at your current stage, but try to follow this guideline as much as you can. Hopefully the users here will be understanding about this fact and help you. They seem to be doing that, judging from this question and others. :)
Again, sorry for the book.
EDIT: I now see that I am quite late to answering this question. (I have a horribly bad sense of time. . .) I hope that is not too heavily frowned upon and Jordan actually has a chance to benefit from this.