How to design the sampling plan?!

#1
I need to conduct an investigate in my province, we need to investigate the Scientific literacy of people in our province. The sampling plan I design is:
1. sampling the cities in our province.
2. sampling the countries in the cities.
3. sampling the families in the countries.
4. sampling the peoples in the families to be investigated.

But if I use the sampling plan above, we will need to go to every family to doing the investigate, indeed it is really hard, many people are not at home, some even refuse to let you in, so my boss want me to design another sampling plan to avoid going to every family.
For examples, we conducted a investigate sever months ago, it is to investigate the features of different jobs of people. So we design the sampling plan below:
1. Devide the people to different part by the gender, age, and jobs.
2. In each part of people, find the people we need and we don't need to go to their homes to conduct the investigate, for instance, if we need to investigate the doctors we just go to the hospitals.

But the trouble is, in the first investigate, how could I devide the people into different part? Just use the gender, age? or jobs?
We need to investigate all the people in the province. It drives me crazy!