Before we get down to the content, you need to decide what aspect of Mandarin you would like to study. Then there a few tools and gadgets you'll find helpful. Take a little time to explore these and register if necessary. (Remember, they are all free and are only mentioned here because they are useful, tried and tested).
Chinese is written using a very different script to English. You need to decide early on whether you want to learn to read and write written Chinese or whether your target is to learn to speak and understand. If the latter, then you may find that, rather than learn to read and or write the characters that make up written Chinese, it is enough to learn to read 'pinyin' or the common way of transcribing Chinese using the roman alphabet. If you are planning to study Chinese characters, there is only so much practice you can find on the internet. If you are happy to learn to speak and understand, then there is a vast and ever-growing amount of language tuition and practise to be found online. (It's probably worth remembering, when making this decision, that there are huge numbers of Chinese people around the world managing their lives very well who can't read their own language).
One activity that can give you an introduction to writing Chinese characters is a neat 'writing game' that can be found on the BBC website:
Now get yourself set up for regular study of this language - but 'little and often' is really the only way to get there.
First, download your free audio flashcards from BYKI (Before You Know It).
These are cards are fantastic for mastering basic vocabulary and the audio is excellent, providing all the repetition that you need to help words 'stick'. The only fiddly part is realising how to change the word list that you are practising. The link is small and right at the top of the page. Click on it and select 'change list' when you are ready to move on.
Another way you can set yourself to make the most of your learning opportunities is to customise the layout of your computer desktop. One way you can do this is to got to iGoogle and, if you don't have a Google account already, sign up for one (it's free and very useful).
You should find a link that says 'Add Stuff' If you search using the term 'Chinese' or 'Mandarin' you'll find various bits and pieces - but I would recommend setting up a 'Word of the Day' gadget or two - like the one shown here. The best ones will give you a recording of the word and embed it into a context.
There are more and more online translators around - and they are steadily getting better, but can't be relied on. This one gives you a fun speech-to-text interface, which might help you out in a pinch - and is quite fun to play with. Just select the language you want to translate from and to and then type in the box.
Another neat tool which can be very useful if you are trying to learn to read Chinese is to be found at MandarinSpot.com.
If you find a website in Chinese you can put the address into the Annotator, click 'Annotate' and the page will be displayed with a translation roll-over - so that as you hover your mouse over a character or characters, the pinyin and translation will be displayed. Clever.
It will also let you copy and paste text in, for 'annotation'.
One of the things that most puts of people when they come to learn to speak Chinese is the use of tones.
The BBC had a good activitiy to begin to train your ear to recognise tones:
You'll find another activity offering tone practice here
If you want an explanation of the tone system, rather than practice, there's one to be found at About.com
One way to see if this language is for you is to try a 'demo' lesson. Mango Languages isn't a free course - but you can try out Lesson 1 for free. This lesson will give you lots and lots of practice of some very basic and useful phrases so it's well worth doing - but this website is all about learning for free so check out what else is there before deciding you would like to sign up for the paid units.