Who claims dependents?

My husband is starting a new job. When filling out the W4 forms, how many deductions should he claim? The form seems different than the one I completed for my job. So he claimed "1" for himself and "1" for me. But should he also claim "2" for our children? Or do I claim those with mine? 

 

We want to limit the amount of taxes we have to pay or get back when filing.

 

For this year, we will be filing a joint federal return but individual for states (I am Montana; he will be split Ohio and Montana).