Welcome Seafarer

IIRC, eat cold steel described the proper way to raid a province. The first part is as described above. Once the province is conquered, the second part to raiding:

1) raze the taxes to very high
2) raise the buildings in the province...

Uh, correction:

1) raise the taxes to very high
2) raze (destroy) the buildings in the province
3) abandon the province

It is that third step I always have problems with - giving back the province.