► Cache component references: Always cache reference to components you need to use your scripts

► Memory Allocation: Instead of instantiating the new object on the fly, always consider creating and using object pools. It will help to less memory fragmentation and make the garbage collector work less

► Layers and collision matrix: For each new layer, a new column and row are added on the collision matrix. This matrix is responsible for defining interactions between layers

► Raycasts: It enables to fire a ray on a certain direction with a certain length and let you know if it hit something

► Physics 2D 3D: Choose physics engine that suits your game

► Rigidbody: It is an essential component when adding physical interactions between objects

► Fixed Timestep: Fixed timestep value directly impacts the fixedupdate() and physics update rate.