I don't think he would like to receive a pink card unless it was to congratulate him on a new baby girl. I don't think he would like to receive a card with lots of frilly flowers on it. Flowers maybe if they were used in a subtle way, perhaps for a sympathy card. Same goes for embelishments. Ribbon is fine if it doesn't have lots of ruffles or bows.
So what would be good choices? Hardware is always good. It can surround a sentiment or just brads to embelish a corner. As for colors, darker shades are my choice. It doesn't mean I don't use red or yellow, but not the bright tones. Rich Regals or many of the Earth Elements are top on my list when choosing for a masculine card. I personally like green for masculine cards. Even Certainly Celery from the Soft Subtle family can be nice if used properly. Dark outline layers/mats can give a darker sence to a card also. Selection of paper can also come into account. Textured paper would be good as opposed to just flat cardstock.
As for image I go one of two ways. There are the typical images like vehicles. I like to go also go for the items that are of significance to the person. My dad for instance has a number of apple and cherry trees that he likes to pick fruits from. I like to use images of piles of these fruits on cards for him.
With Valentine's Day soon approaching I wanted to have something to select from for my DH, dad and maybe brother. I made this card the other night. I think it has a nice balance of male colors, images, and embelishments. It could go to anyone as it doesn't lean too heavily to one side, but I would like to think one of the men in my life would like to receive this card.
The image was colored with my Stampin' Up! Certainly Celery Marker. To get the shaded effect I carefully colored the image with the marker so I didn't overlap any of the strokes. Then I went back and colored again the areas I wanted a little darker. Here is a great tutorial for how to this further. The hardware piece around the sentiment is Hodgepodge Hardware Pewter. The Regal colors of the Real Red and So Saffron are not that bright even though red and yellow would normally be considered a girly color. The black mats also help to give some depth, definition and darken the card. The only part I may consider changing is the ribbon. I think it either needs to be shorter on the tails or maybe a different color. I might try a black one there before sending the card.