L.A.
Okay, so don't tell him "No". What I mean by that is say something like yes, at this point. or yes, after such and such. "yes, we can paint tomorrow." "Yes, we'll paint right after lunch."
Also, empathy is your friend. It's hard to fight back with an agreeing person. "I really want to paint too." "Painting would be fun." "You REALLY REALLY want to paint!" note, none of this is saying okay, we'll paint because you're tantrumming. Then say "we can paint <at this point>."
One really great book that help get the same message across but from a perspective that preschoolers are much more accepting of is "Playful Parenting" by Leonard Cohen. It teaches you to handle things from their perspective. It's not being more permissive, but just translating it. Kinda like Sesame Street teaches phonics with kid tactics not college lecture tactics.
For help understanding strong willed kids, I absolutely love "Raising your Spirited Child" by Kurcinka. It will help you understand your little one as well as give tested advice on how to address them WITHOUT breaking that strong spirit that they are born with. An adult that is tenacious can change the world. However a tenacious child is at risk of being thrown out the window. LOL (not serious)
Learn how to approach things differently, not like you would a rational mature adult, and your battle count will drop about 95%. Been there, have done that. Would do it again in a second!
p.s. both should be at your library and I think both are on audio now as well.