Code Development
As a developer, the first most important component to any effort is what language is going to be the core of the application development. Everything a project might require that falls outside the direct scope of the selected language should be able to be supported by extending that language...in other words, the code base should be able to extend itself enough to incorporate other language solutions.
These are the code development skills I have, focused mainly on languages used in software development. While this list may not be exhaustive, it is relevant.