Bielec,
as a first tool of any investigation, I suggest Occam's Razor.
For those unfamiliar:
Occam's razor (or Ockham's razor), is the meta-theoretical principle that "entities should not be multiplied beyond what is necessary" (entia non sunt multiplicanda praeter necessitatem) and the conclusion there of, that the simplest solution is usually the correct one.
Occam's razor - Wikipedia, the free encyclopedia