How to apply putty effectively?

Start by cleaning the surface you want to putty. Ensure it is free of dirt, grease, and old paint. Mix the putty according to the instructions on the packaging and use a putty knife to apply it. Work in thin layers and smooth the putty out. Allow it to dry completely before sanding or painting. Don't forget to sand it down to a smooth finish and consider using a primer before applying the final paint for the best result.