One of the challenges for newcomers learning any Chinese dialect (including Mandarin), is that the languages are tonal languages. In English, we tend to use tone for emphasis but it's not really used to change to a different word.
For example, if I said "he really wants to go", if I draw out and more heavily the word "really", I can make it sound emphatic rather than casual.
The exceptions to this would be homophones, where we have words that are spelled the same but entirely different meanings. A simple example would be "lead" where you can "lead a horse to water" but also "go down like a lead balloon".
In Chinese, words that have the same Pīnyīn letters but different tones, are usually (but not always) entirely different words. A common example is "ma", which depending upon tones can mean a horse, a mother, a question mark, and many more things. Even when the tones are the same, it can mean many different things, and you need context to make sense of it.
Because of this, what I found difficult at first, is talking to Chinese people. The problem is that if they hear "ma" with the first tone, and "ma" with the third tone, they don't hear a badly pronounced word, they hear an entirely different word. There's no mental connection between the two.
In English, that's not so much of an issue. For example, if I said "there is lead in the petrol" but pronounced "lead" like the one in "lead a horse to water", an English speaker can still understand you, and will just think you have a lousy accent. We have a mental connection between those two words.
I find that Chinese speakers do not have this mental connection. It's probably because we relate the two different words to the same spelling, whereas "ma" and "ma" are often entirely different characters in Hanzi (or Chinese characters):
It's only in Pīnyīn that the letters seem related. To a speaker, they aren't related at all. Only words with the same letters and tones seem related this way.
I'll write more soon on the best methods for learning. If you want to get a taste for it in the meantime though, my current favorite is Tutor Ming. If you decide to try it, click here and it's a bit cheaper for you, and for me.