No matter how much you cleaned your negative ahead of time, you’ll probably need to retouch to get dust spots out. (Most scanners, and in particular those dedicated to film, have built-in dust removal software. While many pros decry it, test it to see if it works for you.) Create a new blank layer, rename it Dust, grab the Spot Healing Brush, set it in the options bar to Sample All Layers, and retouch. Then remove any color casts using a Curves Adjustment Layer. It’s important to make all of your corrections to your master file.