Need to start some were in modding right? Why not try the Half-Life modding Kit. This Kit is designed to have all the tools you need to start your own Half-Life mod, simple mods can be made or advance ones like Base Defense with this small set of tools. If you want to start modding Half-Life you should try this.
Not everyone wants all the other tools in Half-Life Modding Kit 3.0. This version only contains the tools used for mapping such as Hammer Editor and compile tools.