(v5m)to step into (e.g. someone else's territory); to break into; to raid
to come to grips with; to get to the core of
詳しいことが全部わかるまでは、あわててその場にふみこむな。見当がつくまでは、慎重にかまえておれ。 Don't rush into the situation until you have all the details; hold your horses until you know where you are going.