a few tips that helped me:
- plan your game. write down what you want. write sentences, draw sketchs or something else (i prefer mindmaps and textual descriptions).
- list the required features, the optional features and the nice-to-haves (-> set priorities).
- Use the spiral model for your projects. It minimizes the chance of a complete fail. built the main game mechanics and improve it continously.
- view code smaples, tutorials, ask users to find a good technique to realize the needs (for example: how to realize laser-rays? particles? models? sprites? )
- use a version control system (like subversion or git) to track the development and get the possibility to test major changes in your project without destroying your previous work