My personal preference is children's books and television.
If you have a China town section of your local city you should be able to find a book store with children's books in them. You usually won't find these books in a regular foreign langauges store or even large chain book stores.
The alternative is to go to the children's second language section of a local university where you can usually find materials for teaching children Chinese as a second language.
In my local city we have a large Chinese population so we can get plenty of reading material at the local library.
I also like children's television as a starting point to practice reading (subtitiles). If you can't get your hands on some children's DVDs with Chinese subtitles, try the Chinese online streaming video site from CCTV. You can see the children's section here. Most videos have sub titles.
Reading subtitles on TV will help train your brain to read quickl if you already have a good basic vocabulary.