How to build your vocabulary and learn radicals

Once you've learnt a few basic elements of characters you can start putting them together in different ways to make other characters and combining characters to make words like 人口(population). You'll need to work on learning the radicals. There is a complete list on Wikipedia:

http://en.wiktionary.org/wiki/Index:Chinese_radical

Start with the easier ones with fewer strokes and gradually work your way through the list using the learning techniques I've outlined before. The radicals are used in Chinese dictionaries to index the characters in the dictionary. You'll need to learn how to count the number of strokes in a character for that.