What is the ideal range to pull handbrake on and engage so vehicle doesn't move on a hill on a Ford focus climate.
As Paul says, this is highly subjective - the only concrete answer is "pull it on enough to hold the car". The very fact you're asking this suggests to me that it almost certainly needs adjusting....
You should adjust the handbrake (or have it adjusted) so that it is fully engaged (i.e. you can't turn the rear wheels by hand, with them jacked up off the ground) at about 1/2 to 3/4 of the full travel. If it's been adjusted as far as it will go and it's still too loose, you'll need to have the cables and/or the rear shoes replaced.
I would also always recommend parking with the car in gear (or P, if it's automatic) - use first if you're pointing uphill, reverse if you're pointing down, and turn the steering wheel so that the downhill side of the front wheels points towards the kerb.