T-nail practice on Ref File 2

PS CS2
Here is a cleaner presentation of the original.  The file with the reference photo was extended to fit in the work area.  The background layer was converted to a normal layer to permit making a layer beneath it on which to paint.  Above the layer on which the ref photo sits a gray fill layer was added. 

I made the top (gray) layer temporarily transparent in order to see the photo on the layer below to select it.  I did that with the marquis tool.  I then converted the gray layer to a layer mask.  Using a black brush, I painted over the selection area to make that part of the gray layer completely transparent.  I did the same to make the cut-outs below.

I then made the ref photo layer a layer mask as well and painted over it in black (using the cut-out selections made with the marquis tool) to make that part of the photo layer completely transparent (i.e. so that I could paint on the layer beneath it and have it show through.  An acceptable option would be to paint directly on the photo layer - but this is practice, so I made it work intensive.)

To use this set up, you can lock all the layers except the bottom one to ensure that you do all the painting on that layer, behind the gray cut-out.  Obviously, you can arrange the t-nails any way you like - make more, make just one, put them on top, or to the side.  It's all up to you.

So far this idea is all about painting on one layer, the bottom one.  The next step is to extend it to use layer groups.  But for now, it's good enough for t-nailing, which is done quickly and directly on one layer. 

Note: This may seem as if it's about photo manipulation or tech-head stuff, but it's not.  Knowing how to use the tech is essential to doing the artwork.  A big part of this exercise was about using masks, which is advantageous in traditional media, so why shy away from it with digital?  Save the masterpieces until later.  First learn the fundamentals and, oh! yeah.  LEARN TO USE THE TOOLS.        ("Life is short; ART is long." Ain't it a bitch?)

-- Note 9/30/15:  I touched up the original post by extending the top of the canvas so it framed the reference photo above and trimmed the white edges between the photo and the gray matting.  Then I put some time into developing the thumbnails. To do that quickly (it was one O' clock in the morning) I made an exercise of using the color picker. That's not bad thing, per se.  Like tracing, it's a valid means to some ends, so has its place in the digital bag of tricks.  But, it shouldn't take the place of the artist's eye.  Since it doesn't require a lot of practice compared to color matching by eye, it should not be the first choice.  Priority should be given to exercising art skills over digitally facilitated substitutes for them.  Here's where it gets tricky deciding how to use digital tools. Take care not to cripple yourself with them.