By way of introduction I am Tony Cook and I observed my first comet as a teenager in January 1974 - C/1973 E1 (Kahoutek). I imaged my first comet in 2004 and have been imaging comets ever since 
I use a number of techniques to process comet images. You need a variety of techniques as comets have different sizes, brightness's and speeds and this variation requires different approaches for isolating a moving comet from the starry background to get rid of stars that would end up as streaks.
I have written a tutorial on basic processing here - https://www.astrobin.com/151422/
A more advanced method for removing residual star streaks is explained here - https://www.astrobin.com/164855/E/
I also produce 3D images of comets - using the natural motion of the comet to get a virtual baseline for the 3D effect.
I have yet to produce a detailed tutorial on blending comet and backgrounds - other then to say the method I use is based on additive "screen" blending in Photoshop
I use a number of techniques to process comet images. You need a variety of techniques as comets have different sizes, brightness's and speeds and this variation requires different approaches for isolating a moving comet from the starry background to get rid of stars that would end up as streaks.
I have written a tutorial on basic processing here - https://www.astrobin.com/151422/
A more advanced method for removing residual star streaks is explained here - https://www.astrobin.com/164855/E/
I also produce 3D images of comets - using the natural motion of the comet to get a virtual baseline for the 3D effect.
I have yet to produce a detailed tutorial on blending comet and backgrounds - other then to say the method I use is based on additive "screen" blending in Photoshop