If the coat and trousers are different colors, canvas shoes are optional, but the trousers must fit. Converse's new style in spring and summer this year-retro cowhide wrapping series, the color is very good and beautiful, there are blue, orange, green and gray, and blue (low state) is recommended. If you don't like it, choose the classic old one, black and white, and be sure to match it low.
As for the tie, it depends on what color the groom chooses. If he chooses red, you can choose blue and light pink ... as long as it doesn't stand out. I don't suggest taking it. You don't have to wear a tie formally, but you can wear it cleanly and simply.
Another important factor of men's wear is the belt, which will bring better results if properly matched.
I hope it helps you, hehe!