Sure, you can dress yourself, but here is everything you need to know about making sure your clothes actually fit you properly. Let's get started with the suit basics:
SHIRT SLEEVE: The end of the sleeve should fall in the space between the base of your wrist (or that bone that sticks out) and the bottom knuckle of your thumb.
SHOULDERS: The shoulder seams of the shirt should line up with the ends of your shoulders -- where the horizontal plane of your shoulder meets your bicep.
TORSO: Aside from the eye test ("Does this look too big/small?"), the best way to see if a shirt fits your torso is to hug someone (or act out the motion).
COLLAR: The shirt collar should be snug around your neck (no gaps) without feeling constricted.
When in doubt, apply the two-finger test: You should be able to fit two fingers between the fastened collar and your neck. If you have some wiggle room, it's probably too big. If you can't get two fingers in there, it's too tight.
If you're unsure, err on the side of too big. You don't want to feel like you're being choked all night long.
PANTS: When it comes to finding the right pair of pants, you're looking for a straight back with a small "break" (crease) in the front.
Again, the best way to tell if you have the wrong size is to look in the mirror. To ensure proper sizing, you should ALWAYS try pants on with your dress shoes.
Do NOT underestimate the importance of a proper-fitting pair of trousers! Nothing says "I don't know how to dress" quite like an ill-fitting pair of pants.
Also, this is how your butt should look:
JACKET SLEEVE: The general rule here is that you want to show a bit of the shirt cuff, but not too much.
You want to tease your dress shirt, basically. "Oh, I like that cuff. I wonder what the rest of his shirt looks like," they'll all say, probably. Not really. Nobody says that. They'll only talk behind your back if it's too short or too long. Don't let them do that!
JACKET LENGTH: The bottom of the jacket should end right around the natural cup of your hand (the inner curve of your fingers).
JACKET STYLE: Buttons and Body Type
Tall and Thin: Congratulations! You have the freedom to wear pretty much whatever style you'd like: two-, three-, or four-button jackets.
Tall and Muscular/Husky: For the most part, you'll want to go for the classic two-button style, but for a thinner waistline you can opt for a one-button jacket. And please, please, please don't go baggy. Get a suit that fits!
Short and Thin: You'll want to elongate your body with a low button stance (the opening "V" of the jacket should be lower on your torso). Avoid double-breasted jackets along with three- and four-button jackets. Look at Apolo Anton Ohno (the man above) to get a sense of what we're talking about here.
Short and Muscular/Husky: To create a thinning effect and elongate your body, get a jacket with a low button stance (the opening "V" of the jacket should be lower on your torso). You should also avoid double-breasted jackets along with three- and four-button jackets. Seriously, don't do it. You'll look silly.
PICKING A TIE: Match Your Date or Your Outfit
THE POCKET SQUARE: Friend or Foe? (Hint: Friend)
Make Sure Your Belt Matches Your Shoes
RENTING A TUXEDO: Coordinate Colors
The Jacket Button Rule:
How to Properly Iron Your Dress Shirt
Sprinkle the shirt with water. If your iron doesn't have this option, use a spray bottle. If you don't have a spray bottle, use your fingers. If you don't have fingers, you shouldn't be ironing.
THE PROPER ORDER:
Collar - Pop it and start on the back side, ironing from one end to the other. Flip it over and iron the other side.
Cuffs - Unbutton the cuffs and lay them out flat. Iron the inside of the cuff first, then the outside.
Front - Flip the shirt inside out and start by ironing the strips of fabric down the opening of the shirt (the buttons should be facedown on the towel). Then work from the top of the shoulder downward. Repeat this process on the front side. DO NOT IRON THE BUTTONS!
Back - Open the shirt and start ironing from the top of the inside shoulder (the part that rests against your back), working your way down. Do this to the other side (left or right) and then flip it over and iron the back of the shirt in the same process.
Sleeves - Flatten out the sleeve and start ironing at the wider end, working your way to the cuff. Turn the sleeve over and iron the back. Do this for both sleeves.
Don't forget to hang your shirt when finished.