You need to figure out what the average wage for your occupation is in the area that you will be working, and then make sure that your wage is at least as much as that average. That's how it works with BC PNP - there might be differences between the provinces, but that should give you a general idea. All PNPs basically want to make sure that if you're working in Canada under PNP, you get paid the same amount or more than what a Canadian worker would be getting - that's to ensure that foreigners don't come to the country to work for lower pay and therefore cause Canadians to not be hired because they want to be paid more.
Go to this address http://www.jobbank.gc.ca/LMI_report_area.do?reportOption=wage&PROVINCE_ID=35&GEOAREA_CD=9219&selectLocation=Continue and type in the city you work in. Then search for your NOC code or occupation, and look at the wages that come up - you should make at least as much as the median wage.
I'm not an expert so this is not 100% guaranteed correct information, but this is what I was told by my immigration lawyer when I was applying for BCPNP.