I learned this cool technique. I learned it as ‘Picture in Picture’ which reminds me of that feature I never use on my tv. Apparently it’s all the rage with Snapchat and such. Being behind the times (where I pretty much live), I had never heard of or seen it.
The idea is you take a photograph of your hands holding your phone, and put them on a blank layer (transparency) in Photoshop. Then you take a photograph and fit it to the background. Cut and paste the same photography INTO (Paste Special) your picture of your phone. (Use the polygonal lasso tool to make the selection of your phone screen.) Don’t forget to blur background layer for best effect.