Step 1
We have such law in Poland... and one of the lowest birthrates in Europe.
I have a better idea: decrease obligatory employer's ZUS/health service contribution by 30% for the first child of an employee, 60% for the second, and 100% for the third. It would mean that people with children will be much more attractive on the job market and will have more stable jobs.
Introduce generous child benefits and tax reliefs for parents. Stop persuading childless parasites to have children - they should be allowed to discontinue their retarded genes - just tax them more and work on those who already have children, so they decide to have more of them.
Another benefit of such system would be that it might force the childless to take their stench of death with them and emigrate. This way the society would consist almost exclusively of people who have children (the more the better).
Also, in popular culture, mass media, and higher culture pro-natalist attitudes have to be promoted and presented in best possible light.
If we apply all this, then Satan - with his hedonistic, retarded culture of death - will run away with his tail between his legs. So help us God.