Almost every man will find occasion to wear a suit once in a while. The two-button black suit is perhaps the most classic, and certainly the most versatile. Think of the salesperson as a resource, not a nuisance. Get measured, even if you think you know your size. Explain what you're looking for and ask for advice. A good salesperson will know what design details in a suit will best suit your features.
Start with an undershirt. Undershirts protect your dress clothes from perspiration and hide their translucence. Now add a white dress shirt-once again, get measured! Add a solid colored necktie, black dress socks and dress shoes and you're almost there. Once you have the basics you can add pieces like a striped or solid shirt of another color. Ties are one way to express yourself, with different pattern or statement ties.
A black dress belt is a must. Better yet, buy a reversible dress belt that easily switches from black to brown. If you own a dress watch with a metal band, choose a dress belt with a buckle that matches (silver or gold). Also buy a casual belt (usually wider and less shiny) to wear with jeans or other casual pants. A properly fitting belt should be comfortable when set to the middle notch. You want your belt to match your shoes, so if you buy a pair of brown shoes, try to find a belt of a similar color leather.
Twill pants, often called khakis or chinos, are an absolute must! Dress them up with a dress shirt, tie, and blazer, or dress them down with a polo shirt. A blazer is optional, but very snazzy-the most classic look is a blue blazer with brass buttons, paired with khakis. Wear dress socks that match your pants.
If you find you are getting a lot of wear out of your khakis, start to build your wardrobe with a few other color pants such as black, olive green and other shades. All neutral colors, you can mix these pants with other white, black or neutral color shirts.
Darker, unadorned, straight-leg jeans have an enduring quality. If you only own one pair of jeans, choose some of this style. Avoid jeans that are extremely baggy, too short, or excessively distressed. Jeans should be worn with matching casual socks and a casual belt. Sport shirts or t-shirts go well with jeans. For some occasions you dress up a pair of jeans with a blazer. Make sure your jeans are in good shape, and you can wear a button down shirt and blazer, or go for the Steve Jobs look with a turtleneck.
If needed, a dressier coat such as a peacoat or trench coat should be worn with suits and more formal clothing. "Hoodies" and sweatshirts should be reserved for jeans and other casual clothing. Sweaters are great for layering and can be worn over a dress shirt under a suit coat or blazer, or over a sport shirt with a pair of jeans.
Match leather. Belt, shoes, and watch band should be the same color. Leather accessories such as briefcase or padfolio can match too, but are less critical.
Match metal. Metal watch bands and belt buckles should be the same color.
Match dressiness. Wear casual accessories (socks, shoes, belt) with casual clothes and dress accessories with dress or business casual clothes
Match socks and pants. Blue jeans should be worn with blue socks, black pants with black socks. Save white athletic socks for the gym. If you are adventurous, you can get a pair of statement socks with stripes, argyle patterns or even characters.
Extending the Wardrobe
Buy more of what you wear more frequently. If you wear a suit every day, buy several suits. If you wear jeans, buy more. Buy different colors and styles. Look at what the people around you are wearing, and find a balance of conforming to style guidelines and expressing your individuality.
Also, remember that you don't have to buy everything at once. Start with what you wear most frequently and buy what you need as the need arises. Take advantage of sales and even thrift stores, and make use of what you already own.
Finally, consider that while the clothes may make the man, style is about more than just clothing. Proper grooming completes a good look, but even that isn't everything. Looking good in your outfit is only part of the equation. You want your confidence and assurance to show, and the outfit and the right shoes helps build that state.