Nixon's primary focus of policy that sought to end the Vietnam conflict was the seeking out of diplomatic dialogue between both sides.  Nixon and Secretary of State Kissinger actively sought to open channels with the Vietnamese in order to draft parameters and limitations that could form the basis of a lasting peace in the region.  This is something that his predecessor, President Johnson never could nor sought to do.  In terms of policies that seemed to increase the involvement, Nixon increased the bombing of the Vietnam nation and also saw it spill over into Cambodia and other neighboring nations.  This helped to cause a bit of a tension, or credibility gap, between Nixon and the American people, for on one hand there were active attempts and dialogue that sought to end the war while at the same time there were actions that were intended to increase the scope and impact of the war.

The major example of a policy that seemed to lessen US involvement in the Vietnam War was Nixon's policy of "Vietnamization."  In this policy, the US was supposed to be handing over responsibility for the war to the Vietnamese themselves.

In terms of things that seemed to make the US get more involved, Nixon did some things that seemed to widen the war.  For example, he ordered the invasion of Cambodia, which had previously been off limits.  He also really intensified bombing of North Vietnam.  By intensifying and spreading the war, he seemed to be pushing for more US involvement.