How does a football player increase their momentum momentum?

The simple answer is run faster and don't slow down at the moment of tackling. The other answer is tackle low: it doesn't change the momentum, but it increases the effect of the tackle.

Increase the velocity and the mass.

In order to increase an objects momentum, you must increase the objects velocity or mass. To decrease momentum, you reduce the objects velocity or mass.

momentum of a body can be increased either by increasing velocity or by mass.since momentum = mass * velocity.