Accept your body for what it is right now. Even if you want to lose weight, make peace with your current size and move forward from here. While it is good to pursue a healthier lifestyle, focusing completely on your weight can lead to depression, and depression doesn’t motivate changes (at least not healthy ones).
Wear clothes that fit you now. While you may have been lighter several months or years ago (and you may someday weigh that much again), if it doesn’t fit you now, don’t wear it. Too-tight clothing just draws attention to the fact that you’re overweight, emphasizing curves you may not want emphasized. Similarly, over-sized clothes don’t make big people look smaller, they just make you look bigger. While Kate Moss might look even more rail thin wearing something that is over-sized, this is not the case with larger people. You may even want to go get fitted for a pair of pants, if you have trouble finding pants that look good on you.
Don’t buy shirts that are huge and baggy, thinking it will make you look better. Chances are it will only make you look sloppy. A T-shirt that is two sizes too big will be too wide in the shoulders and neck and hang down below your crotch, making you look even bigger as a result.
If you have problems keeping shirts tucked in, you can change that. Buy shirts labeled “tall”, which are usually available only in large or XL but if you are in that size group, then they will fit you well without being too big. Put your shirt on FIRST, and then your pants. Do not do too much “blousing out” of the shirt, particularly at the front, but also don’t tuck too tight–somewhere in between the two extremes will look best.
Always wear a belt. One that is wide, thick, and sturdy will work best, and you should wear it tighter with a tucked shirt than with an un-tucked shirt (a wide belt will feel more comfortable if tight than a narrow belt will.)
Find clothes that fit the largest part of your body and have them tailored. If the pants fit in the waist, but are busting at the seams at your thighs, buy a larger size that fits your thighs and have them taken in at the waist. It is better to pay a little extra for pants that fit you perfectly than $50 for pants that don’t.
Wear vertical stripes. Even a faint pinstripe (which is very in right now) does wonders for creating a nice vertical line. Make sure that the stripes are on clothes that fit you because even a simple pattern like a stripe can accentuate clothes that don’t fit and make you look enormous instead of giving you the slim look you’re trying to achieve.
Wear straight leg pants with no pleats. Straight leg pants (meaning as wide at the bottom as at the thigh) keep you from being V-shaped with tiny ankles and a wider midsection. If your pants fit, you don’t need pleats.
Don’t add extra bulk to your body. Cargo pants, hoodies front pouches, bulky sweaters, and the such can make you look bigger. Shoulder pads are also a generally a no-no. While natural materials are generally preferable, synthetics can help you cut down on bulky clothes during colder seasons.
If you have anything large that you would normally keep in your pocket, you may want to invest in a messenger bag or suitcase large wallet, giant cell phone, a large keyring, a PDA, writing utensils, and a pad of paper. While nobody wants a man-purse, lots of things in your pocket just add weight to your waistline. For a very professional look, invest in a high-quality briefcase.