Which commitment should I make? I want to make one commitment now to save myself from suffering in distant future.
The kind of suffering is same as due to unity with undesired situation. For example I might have to shake hands with my enemy. Or I might have to live under poverty.

Which single most important commitment should I make to follow every day or every moment or every week so that I may not suffer while getting united with the undesirable? 

(Answer should be like start keeping right view or start practicing right view or I should start jogging or I should start meditating or start chanting mantra etc...)
One could simply commit to the awareness of:


  This is not mine. This is not my self. This is not what I am.


Notice that quote is prefaced by the following introduction that addresses the question's focus on action and consequence (i.e., form):


  Rahula, any form whatsoever that is past, future, or present; internal
  or external; blatant or subtle; common or sublime; far or near: every
  form is to be seen as it actually is with right discernment as...


With right discernment comes a relinquishing of self and an openness to other questions and other suttas.

Also, given the expressed concern about consequence, there may be fear and terror here, in which case the Bhaya-bherava Sutta: Fear &amp; Terror Sutta may be a helpful exploration.