Change things around and bring him flowers, chocolates and a sincerely meant compliment. If you can bake make him a cake, a pie or cookies, homemade may not be perfect but it's far more intimate/ personal than something from a bakery. Stop suggesting changes to his wardrobe and bring him flowers in bright colours instead. Later you can try a shirt or tie, inspired by the colours he liked in the flowers. Or, not, really how terrible is it that he dresses himself, even if you don't approve of some of his choices. Keep in mind that he wants to look good, he just doesn't want to be told to change. A compliment will work much better. Tell him when he's looking good. Tell him he's having a great hair day. Tell him those pants look great on him, that shirt brings out the colour of his eyes and he looks so polished and professional when he wears that suit. People like positive feedback, which is what compliments are. No one is going to accuse you of nagging when you give a sincere compliment to them. (Don't try turning negative feedback into a compliment - that's just mean and phoney). Complimenting men is fun, once you get started. Compliment random men. The guy who held the elevator or the door for you. Smile when you say "thanks" and actually look at him too. Such a small thing can really make a difference in someone's day, for both of you.
Being pleasant never goes out of style.
Guys love compliments ‘As men, we crave compliments. Nothing will make us happier then to be told we look good, smell good, etc. This is why… we men tend to compliment women too much sometimes. We sometimes over use the golden rule, we treat women as we want to be treated. ‘I have worked with some pretty attractive men who would get hit on often which was nothing for them but the second someone actually complimented them they lit up like a god damn gorgeous Christmas tree.’ – BetamaletimQuote from a post at Marie Claire.