Frankly, this is only partially a legal question - mostly it's just about what makes most sense for you, personally. Anyway, I'll try to help.
I expect my ex to violate our brand new, court approved, negotiated
divorce decree.
Should I keep a log of such transgressions?
Yes - why not? It costs very little (just a bit of your time), and while it may not turn out to be useful, it could very well be:
- to show to others (lawyer, judge) that a transgression happened repeatedly
- to better explain the history of the problems between you
- to help yourself better judge the situation (is it getting better, or worse?)
So just grab a notepad (or a computer file, or whatever) and make some short notes when something significant happens.
At what point should I seek legal help to enforce compliance:
financial and otherwise?
Some options seem to be: At the time of the first transgression, After
a certain number of transgressions, When the dollar amount goes over a
certain amount.
Now this is not really a legal question - the answer is: it depends. Legally, you usually do not need to tolerate any transgressions (details may depend on jurisdiction and nature of settlement), so you could probably sue even for trivial transgressions.
However, in practice pursuing legal action comes with a cost:
- your time, for researching and talking to a lawyer
- your money, for the lawyer, court and other costs
- possibly your peace of mind, if you find it stressful to pursue someone in court, to have heated discussions etc.
Of course, if you successfully pursue a transgression, this will have upsides, too. So, as always in life, you must weigh both and decide. A good lawyer should help you with that (though for a fee). If you have a specific legal question, you can also ask here :-).