Here's a few pics of my Miter saw set-up. The first thing I did was make a 'zero clearance throat', easily made by copying the original(which is practically useless!)
As can be seen in the pics, I made fences with a track system so sub-fences can be added to suit whatever's needed. Positioning of the sub-fences for a particular cut is easily accomplished and then 'Voila' perfectly backed up cuts!! I've never found a need for 'toggle clamps' to hold the pieces to be cut but could easily be added, typically I use a special block to hold the pieces, which holds the pieces tight to the fence and downward as well!