After completing some 300 trees, I thought it a good idea to reshare my techniques with all of you again. First of all I cut wooden BBQ skewers in half and sharpened both ends with a pencil sharpener. I then bulk stained them in a paint roller trough. 
While they were drying I tore apart cheap blue fiber furnace filters into three layers (like Oreo cookies) I then spray the layers on both sides with either flat black or dark green. Or immerse them in a trough of paint. After the sheets have dried, I cut them into poker chip size and smaller circles. I grind up WS foliage clumps of three green shades, or three shades of Fall colors, in separate piles. (Or grind up florist’s green foam). Keep the scraps for making background trees (with a light blue mist spray) I used to then squeeze on circles of Elmer"s glue, but have eliminated that step, since only the outer leaves are visible. 
My new technique is to press on four or five layers of circles, separate the circles, spray with either spray adhesive or hair spray, then dip them in the pile of ground up colored foliage. I usually use two or three different colors. Note the colors on these Fall foliage trees.