The material determines the type of drill and how it's used. For soft materials, like wood, you only need the drilling mode. To drill in hard materials, like concrete or stone, activate the impact mechanism.

Besides the type of material, you should know two things before you start drilling:

How large do you want the hole diameter to be?
How deep should the hole be?

The choices of drill bit, correct operating mode and best rotational speed depends upon the answers to these questions.

As a rule of thumb, please consider the following:

Soft materials (wood, plastic and metal):
HSS drill bit drilling mode

Hard materials (masonry, concrete):
Masonry drill bit, impact drilling mode

Small hole diameter: 
high speed drilling

Large hole diameter: 
low speed drilling