Advice for perfomance and efficency

I wonder if experienced game developers give advices in respect of the topic.
I.e. the most common newbee’s mistakes that have negative impact on game perfomance. Especially for 2D games, 2D physics and sprites.

  1. Try to minimise Draw-calls , poly-counts and material.

  2. Use Atlas to combine textures and materials.

  3. Use combined meshes instead of using different mesh for objects.

Check this.