I just want to add my two cents on using a mono leader for trolling for the benefit of guests to this site.  Lots of people use mono leaders and they all think that they catch more fish because of the mono leader is harder for fish to see.  I personally see no benefit to using a mono leader.  I know lots of people on this site will disagree with me.  I just think that braided line is so much better than mono.  So if you are new to trolling for lake trout go ahead and use braided line tied directly to a snap.  In my opinion there is no benefit to using a mono leader and several disadvantages.