Before you can write any sort of code, you'll want to have a tool that lets you edit your AddOn files. However do not get overly distracted with the tools themselves while trying to get your first AddOn created. Any text editor, like Windows Notepad can edit the files. All AddOn files are plain text files. The editors can make the coding and many repetitive tasks easier for day to day editing, but it's often very difficult to learn the tools and try to learn the AddOn at the same time.
I also wanted to note that a lot of users, I found on the Web claimed Dugi’s Guide to be faster. However, all these users had either used Zygor Guides for very little time or had not used it at all. I have to give a point to each Dugi’s Guide and Zygor Guides as they both deliver a great lvling speed. For all you Dugi’s guide users out there who really feel that Dugi’s Guide is faster, I will give Dugi an extra point. If there really were a difference, it wouldn’t be by much.