Well developing in a language without a specific IDE for itself might be too much for a beginner. Fortunately we have some very cool and nice IDEs available for us.
1. FlashDevelop (Based on SciTE)
2. FDT5 (Based on Eclipse)

While both these IDEs are free, FlashDevelop is windows only. But I am surely in love with FlashDevelop. FDT is good but being on Eclipse, it takes up a lot of memory, on the other hand FDT runs on all platforms. So choose your weapons and get ready to haXe it all.