Dress for a man is much easier than for a lady, and much easier to define than casual attire.

In General

Generally, dress means a suit and tie.  A sports coat instead of a suit might be appropriate on occasion, but it tends to indicate a lesser level of importance for a man, particularly as it relates to his career, if worn too often.

The Suit

The suit should be wool, linen, or other natural cloth.  Polyester is not a natural cloth.  No petroleum products allowed.  Yes, I know they're cheaper, but cheap is what they communicate.  Leave them behind.

As for color, I prefer the corporate uniforms of black and navy blue.  An occasional gray is good, or a lighter blue.  I wouldn't be buried in brown, it just doesn't look right on me.  Brown does typically look good on dark skinned men, particularly African Americans, but the real issue is a matter of personal taste.  If you feel that it looks good on you, it probably does.  But don't buy any color just because it would be different, get something that you feel complements your appearance.

One note about the suit.  When you're at your desk, or riding in the car, it's usually more comfortable to remove your coat, I often do.  When you do, do not hang it on the back of your chair, and then sit on it.  If you do, your coat will look like you hung it on the back of your chair, and then sat on it.  Hang it elsewhere, so that it will stay neat, or in the car, if you have no back seat passengers, then lay it out neatly in the backseat.

The suit should fit nicely.  Here is an opportunity for me to say that we owe it to ourselves to keep our shapes in order.  Regular exercise, combined with careful eating keeps us in shape and looking good, and indicates to others that we are not lazy and have control of our lives.  There truly is only one way to stay trim and in shape.  Regular exercise, and controlling our diet.  That's it, no others that last.

But, back to the fit, bulging chests are for the ladies.  Your coat should not bulge when buttoned, and you should button it when you're standing.  If the breasts bulge, then you're selecting your suits too small, or you've let your weight get away from you.  Perhaps you've been working out and your chest is getting bigger.  Good for you!  But, you need to get a larger suit now to accommodate your new svelte self.

Your pants should fit well so that your belly doesn't seem to hang over your waistline.  Again, this might mean that you're selecting your pants too small, or that you need to go to the gym more often.  Also, take a look in the mirror at your tailgate.  If your pants are fitting really tight in the rear, we all wish you would get a larger size.  Tight pants are great for blue jeans (or black jeans) but not for a business suit.

The pants should fall gently on your shoes, so that there is a slight "wrinkle" at the bottom where the cuff meets the pants.  I recommend cuffs, by the way.  They have a dressier appearance, and give you a very classical look.

The Shirt

The shirt should be conservative, although occasionally a dark colored shirt that complements the rest of the outfit is nice.  I sometimes wear a maroon shirt with a black and maroon tie and a black suit.  I also have a medium gray that I like.  But, you usually can't go wrong with white, although putting some color in your shirt does show some courage and individuality if you pull it off well.  Be careful that your shirt, tie and suit blend well together.  Always wear a white t-shirt (no writing on it) beneath your shirt, this is important. 

Honestly, I unabashedly admit that I frequently seek the advice of a woman, usually my wife, regarding the colors.  Women can see colors in ways that men can't, in general.  If there is a woman in your life who dresses well, solicit her assistance.

Footwear

For shoes, you can't go wrong with black wing tips.  Again, it's the corporate uniform and for a reason.  They look good.  Slip on loafers are okay if you're wearing a sports coat and slacks, but not with a suit.  Get back to the wing tips.  Socks should be dark, and the same color as your pants.  Shine your shoes, you would be surprised at how many men and women look at a man's shoes to form a subconscious opinion on his attention to detail and demeanor.

More Help

You can get some excellent help from a good men's store or an upper level department store regarding fit and selection.  You will not find this type of assistance at the chain discount store on the freeway, so it's probably best to skip that.  A good suit is going to cost you about $200 or more, but it's well worth it, and you only need six or eight to have enough to wear with variety every day.  Isn't that better than what the ladies face?  They need many more outfits, and the cost of a good ladies suit is at least that of a man's.  Spring for a little investment in your appearance, and it will pay dividends in the impressions that you leave with the people who count in your life.