Shirts. Shirts need to be ironed with abundant starch. You'll feel a crisp new man as you walk out the door, especially if you are prone to patting yourself on the back. There are two ways to approach this: pay someone else to do it for you or learn how yourself. It's pretty hard to find good help these days, but if you don't have the time and can afford it, take the first option. If you want to learn how to do it, then discover the meaning of patience. Be as the monk who rakes the pebble garden. It can be relaxing and the perfectionist in you might enjoy it. I was going to link to some sites with instructions, but they all said iron the collar first and I iron it last. Just use your mojo.
Pure cotton is where it's at. Don't forget it. The Italians have this pretty much sorted, but it is nigh on impossible to find a decent collar these days. Even some fancy shop that sells only shirts will have a thousand of them with exactly the same collar. Stupidity. The collar serves to complement the face. If you have a fat neck, it needs to slim you. If you have a pointy chin, it should square your head up a bit. Don't look a fool for fashion and buy a shirt with a collar that might cause you to take off if an updraft catches you unawares.
Ties. I beg you, don't make a knot that is larger then your jaw. You may be able to get a job as a Channel 10 newsreader but you won't get my respect. Keep the knot small and get the dimple right. It just takes practise. I prefer the four-in-hand knot, but there is no way I can teach you how to do it. I think I was 26 when I finally learned how to tie a tie and it was a complete surprise to me.
Colours. The secret here is to work with your complexion. This quite possibly refers to the level of contrast between your hair colour and skin tone. If you are dark with dark hair, then a high contrast look will work well for you, like a gray suit with a white shirt and a black tie. That's a classic example, if you have a more muted complexion, then ask someone else how this works, my name is not Jeeves.
The rules of pattern. If you are going to mix different patterns then keep them in scale. If you are going to use the same pattern, then vary the scale. Not that hard is it? For stripes, this means that the lines should not be contiguous between the shirt, tie and suit. Work outwards from the shirt increasing the scale as you go.
Pants. The pleated front will always give you a classic look and offer a slimming effect if necessary. Pants with cuffs will always drape better, especially if you are tall. Call me old fashioned if you like.
Suit. The jacket thing that matches your pants. Whatever you do, don't buy a $100 suit from a men's chain store. That's made of polyester you know. Buy a decent pair of pants and get the shirt and tie right instead. Respect. Off the rack is always risky. There are mature ethnic gentlemen throughout the obscure suburbs of Australia who excel at the art of providing excellent tailor made garments. Just pick the right cloth and when you get fat they can let out your pants adding years of extra wear. All this for less than the cost of a root canal. Which would you prefer?
Socks. Tempting to neglect but the right socks seal the deal. Their colour and texture should draw together your entire ensemble. I like to incorporate an element of the tie here. Get this right and soon people will consider you to be more charming than Cary Grant.*
Shoes. Shoes should be comfortable above all, but shiny too and made of leather.
Lastly don't forget - it's what's inside that really counts.