A collection of further, high-quality reading material:
- Git Branching Tutorial - learn git properly
- Git Book - learn git thoroughly
- Networking - basics of networks from the perspective of your home
- Game Programming Patterns - useful for more than just games
- Linux Workstation Security - a checklist for security (should adapt for your own situation)
- Refactoring (2nd Edition) by Martin Fowler.. Not even out.