Honestly, I find color to be the single most difficult element to restore. I’ve tried one technique after another, but recently developed a combination that works for me.
So here’s a tip: try using a series of masked color adjustment layers, varying the opacity of each layer and “painting” the image where you want specific color to appear. I’m liking the result.
PS This is not the only technique I used on this 30 year old photograph, but it was the one that created the greatest improvement.