When it's time to buy a suit, you should go in with an idea of what you're looking for. Color, fabric, and number of buttons are just a few examples of the choices you'll be making. No matter how much you're looking to spend, you can find something that will look great if you know how a suit should fit. Getting a custom made suit with your measurements will always be a better investment than something off the rack. Remember, a custom suit requires around 20 measurements to ensure a great fit. A department store works off of 1 measurement for the jacket and 1 for the trousers.
Know what fit you like. Specifically, do you like a snug fit or a looser fit? Sounds basic, but if you know what fit you want, and you see a suit that doesn't fit your mold, you can move on immediately.
Here are some of the basic components of a suit that you should be familiar with:
1. Shoulders: The suit's shoulder's should hug yours. The shoulder pads shouldn't stick out past your shoulders. If you stand against a wall and the suit touches the wall before your arm does, the suit is too big.
2. Chest: You should allow for a fist's worth of space between your chest and the button when you have the suit buttoned. Not too tight though--you shouldn't have to strain to button it.
3. Length: With your arms hanging down, you should be able to cup your fingers under the sides of the jacket. Some styles have the jacket fitting shorter than that.
4. Number of buttons: Now we're getting more into the style of the suit. A 2 button suit is the classic, and is currently the most popular. The 3 button was popular for quite sometime, but can make you look '90s if you're not careful. If you can find one that doesn't look too high cut (you're not in the NBA) and that preferably has a roll-over lapel (you can button the top button or just do the middle button, the soft lapel will naturally roll over the top button) then the 3 button can be an acceptable choice. A 1 button suit is a bit more rakish but can be a good look if you're a bit more daring.
5. Vents in back: A center vent is all-purpose. Both modern and traditional. Side vents (2 vents on the side instead of 1 in the center) is a bit more stylish. No vent is a no-no.
6. Lapel: A notch lapel is the most common. Always a safe bet. A peak lapel is what you usually see on a double-breasted suit, it's the lapel that points upwards instead of sideways and now is quite common on a single breasted suit. They look a bit more elegant.
7. When you're trying suits on or being measured for a suit, make sure you're wearing dress shoes.