While I know open clusters are one of the least imaged things at Telescope Live some have been imaged they make a perfect target even when the moon is fairly bright too! I may book one we haven't seen imaged soon.
One of the first things I do on open clusters in Photoshop is to use the hue and saturation adjustment layer on the individual colors in my open clusters to make them really pop. I will adjust the lightness down slightly and increase the saturation. I leave the hue alone. The ones I
work the most are the reds, yellows, blues, and cyans. I will decrease lightness and saturation quite a bit on green and magenta. I then flatten the image.
Next, I generally open the selective color adjustment layer and again work my reds, yellows, cyans, and blues to get what I want. I leave green and magenta alone here. I will then flatten the image.
After this, I will generally go back to the hue and saturation adjustment layer and will mess with the lightness sliders only to kill off oversaturated halos and get it to what I like. I then flatten the image again.
Now I am ready for final adjustments with levels and noise reduction if needed, but since it is open clusters I don't do much because they normally do not need much. Using these simple steps can make an open cluster really pop.