You may want to research these sorts of topics since they have been brought up throughout the forum previously and recently. If your new to 3D modeling or looking for ways to get started (Aotrou) goes into depth about this.
If your getting started in 3D modeling or wanting to improve your skills practice is the only key to getting better. I would recommend starting with blender gurus beginner tutorial to get the basic understanding on how things work and its a great place to start if your rather a beginner, however it takes practice and patience to get better at something. Refer to the main threads below;