I have several posts about Gtk+ but I forget
to mention about what need to prepare for programming Gtk+.
1. A Programming Language
~ Well, first as you read my blog entries, I use C to program Gtk+; however, there're Gtk+ libraries support for other programming, too. Such as Perl, Ruby, Python, C++, PHP. It's your choice to pick up any of those languages that fit you most. Make your style and improve your skills.
On the other hand, if you tend to focus on code performance, I suggest C since almost all of the programming languages are based on traditional C language.
2. Utilities & Tools
~ If you want a simple style, then just pick a text editor and use command prompt or shell terminal to compile sources. That's fine! Also, you can setup your own programming environment by taking advantages off all-in-one (AIO) IDE, such as: CodeBlocksIDE, Eclipse, NetBeansIDE, KDevelop, QtCreator (new), Anjunta.
~ Taking advantages of visual interface design for Gtk+, you'd better use Glade Designer. Don't design UI manually! 
It's freaking tiring and time-consuming like crazy...
3. Documentation
~ Things cannot be understood without guidance. It's true, isn't it? Make sure you check and loop up Gtk+ documentation always for references. It's a good habit to confirm everything and memory them.
~ Well, just original documentation doesn't seem to work on you, why not searching out of Internet for examples and guides
? It would be much clearer from other sources' references, too. Learn yourself good searching skills over the network through Google, Live Search (bing.com), Y! Search... they're pretty helpful for you, not only for programming but also other facets of life.
That's all I want to say! Any question? Ask below.....
Have fun!@