While the world may be leaning toward more casual attire, there are still a number of faux pas you need to avoid regardless of the occasion or dress code. These include:

1. Wearing The Wrong Colours  All skin tones are not equal. The lime green or hot pink that you saw on the catwalk may look fabulous on the models, but horrible on you. Experiment with different colours and stick with the palettes that suit you, regardless of what is the latest fashion. Don't waste your money on clothes that make you look pale, sallow, jaundiced, or washed out.
2. Wearing Too Small a Size  If it doesn't fit, don't wear it. Squeezing into a size 10 may feed your vanity, but it will make you appear overfed to everyone else. Shop by FIT, not by size. If you can't sit down in it you're not going to feel (or look) your best.
3. Inappropriate Makeup   Light for day, heavier for evening, sheer for sports or other strenuous pursuits. You wear different clothes for different activities in you life; your makeup should change as well.
4. Running Repairs  If your clothes need taking up, letting down or even just the seam re-stitching get it done.  It will make the clothes hang the way they were designed to and look much nicer. If you're not confident enough to do it yourself call a seamstress
5. Rundown Shoes  You look great...from the ankles up. If your shoes have seen better days, find a good shoe repair shop and put them in for some TLC. Polish them regularly. Use a felt tip marker on scuffs, and put a piece of soft carpet under your feet when you drive.
6. Broken Nails, Chipped Polish  Keep your nails clean and evenly trimmed. To make repairs quickly, have clippers and a nail file in your handbag. Paint over chips or remove all polish. Visit your local beautician to get a manicure
7. Slips That Show  Unfortunately, one length does NOT fit all. You want to emphasise the sheerness of your garment - not draw attention to your slip.
8. Underarm Stains   First, buy deodorant that works with your body. You may have to try a few to find the best one for you, and you may need to change every now and again if your chemistry changes, like after having a baby, starting new medication, going through menopause, etc. My personal favourite Dove Pro-Age roll on. If you perspire heavily or need a surefire method to prevent stains, consider using dress shields.
9. Badly Fitting Bras  Make sure your bra fits properly. If it rides up in back, slips off the shoulders, or lets your breasts sag instead of offering support, then it's time to seek professional help. 
10. Go Back to Your Roots   Hair colour can do wonderful things for you, but it can also be hard on the budget. If you can't afford the regular maintenance required by all over colour, consider getting highlights instead, your hairdresser will be able to advise you on the best choice.

Take a few minutes to attend to the details. Why spoil your look when looking great is nearly as easy?