There is not 1 way of doing this, everyone will find what works best for themselves. I use the Black background with a Tiff. I find that all I have to do is load it into Gimp. Done, Nothing else to do, I don't need to play with the blue or what ever color. I just save the PSD file to use any where else. I don't have PhotoShop, I have PSP8.1 and Gimp. Different programs, different ways. All we can do is give as many tips as we can and hope some of it works for others. 1 last tip, render twice the size you want your finished image to be, better for postwork.