FIT: Figure out what your ideal fit is and get anything that doesn’t fit perfectly adjusted to your physique. It’s a little on the costly side, but it’s well worth it. (Alternatively, you can learn to make basic adjustments yourself; however, I despise doing things and would rather pay someone else!) If you can’t afford a tailor, you might be able to find specialised brands with off-the-rack cuts and designs that fit your body better.
COLOR: Another option is to choose a sophisticated colour scheme. Figure out which colours suit you the best (you can ask a friend or pay attention to colour of the items in your closet that you always gravitate towards and that you always feel good about wearing). A more muted colour scheme, in my opinion, looks the most elegant. Gray, black, beige, camel, white, dark red, dark green, and so forth.
CARE FOR YOUR THINGS: Take good care of the clothing and shoes that you have. Don’t wear worn out shoes (there are also things you can do to help ensure that your shoes wear well, such as waterproofing them before wear, storing them gently so they don’t get banged around or squashed, and alternating pairs. Seriously, this makes SUCH a difference). Learn washing methods that minimize wear and tear. Some items need to be washed per use, but many can be worn several times before needing to be washed. (Do a sniff test). This will help your clothing last longer.
SHOES: While on the topic of shoes, wear stylish shoes. Usually a good mid-range brand will have some great options.