Calculation settings

How to be sure that my settings are good for a fast calculation of my projects ? (rendering)
is that a specific setting to do that the defaut parameters would be ?

Assuming Cycles rendering, start here:

thank you this is exactly what i was looking for.
But i don’t have the right graphic card, (radeon hd 5850) to use CUDA
do you have a suggestion of a good graphic card (not expensive) to use blender confortably ?
i 'll use adobe premiere also…