Below are the steps I take when I am compositing multiple photographs into a single piece of composite photography. For a lot of the steps I have written tutorials you can find by clicking the links.
Especially the double RAW technique is a very easy way of extracting the most out of your RAW files, or even JPG files if the compression isn’t too high.

Composite photography

1. Shoot studio photo and location photo’s. The location photo’s I often shoot as HDR.

2. Shoot background image
HDR photographing, camera settings, etc

3. Retouch model photo
Adding detail using the Double RAW Converting technique, skin retouching (using the dust & scratches filter), dodge & burn
A frequency separation technique is explained very well on Fstoppers by Julia Kuzmenko.

4 Background editing
Tonemapping, Adding detail, cleaning up, dodge & burn

5 Creating the composite
Cutting out the subject, adjusting

6 Creating shadows

7 Blending foreground with the background

8 Final touches

9 Publishing the end results
Use of social media