How I shall drive Maruti Suzuki Ertiga to climb extremely high road?

Use lower gears, not just first gear all the time. In a Maruti Suzuki Ertiga, climb steep roads in the gear that lets the engine stay responsive without struggling, usually 1st for very steep starts and tight hairpins, then 2nd on less severe sections. Avoid half-clutch driving, do not stop mid-slop