If an attorney tells you that proving a breach of fiduciary duty claim in New York is simple, your antennae should be going up for one simple reason: it's just not true.
In fact, the difficulties facing you when you make such a claim are manifest from the very outset of the case - in preparing the complaint. While the elements that you need to prove in order to prevail on the claim aren't necessarily spectacular (The elements of a cause of action to recover damages for breach of fiduciary duty are (1) the existence of a fiduciary relationship, (2) misconduct by the defendant, and (3) damages directly caused by the defendant's misconduct (Rut v. Young Adult Institute, Inc., 74 AD3d 776 [2010])), there is one factor that certainly merits special mention:
A breach of fiduciary duty cause of action must be pleaded with the requisite particularity under CPLR 3016 (b) (see Parekh v. Cain, 96 AD3d 812, 816 [2012]; Palmetto Partners, L.P. v. AJW Qualified Partners, LLC, 83 AD3d 804, 808 [2011]; Chiu v. Man Choi Chiu, 71 AD3d 621, 623 [2010]).
Basically, unless you have sufficient evidence and particulars that allow you to specify in detail how the defendant breached their fiduciary duties to you, and thereby caused you damages, your claim is liable to be dismissed at the very outset. Stated differently, general allegations will not suffice.
In case you were wondering why that is important, consider this: at the outset, you may not have ready access to the information and evidence you will need not only to prove your case, but to get out of the starting gate.