Not getting regular hair cuts - YOu will end up with quite bad spilt ends which you'll end up needing to cut off anyway and your hair will start to look obviously overgrown and thats not a look you wanna go for.
Washing your hair everday - It can be good for your hair to get a break from daily washing, drying and styling. Skipping the shampoo on occasion will help colour stay richer. Try every other day washing and if your hair looks oily on day 2 use a tad a dry shampoo or hair powder on the roots.
Using too much conditioner - If you use too much product on your hair, it will build up and cause the hair to look dull and lifeless. Only apply the conditioner to the ends of your hair
Overheating your hair - You may be literally burning your hair, to protect your hair use a something to specific protect from the heat
Fighting your hair's natural texture - There's wrong with trying to straighten or curl your hair, but if its humid outside you may just want to leave it at it natural state because the second you walk outside it will turn back to it.
Choosing the wrong styling products for your hair type - You need to select the right hair products so that your hair will look its best just like you choose products for your skin type.
Thinking that more is better - Even if you're using the right product, using too much can still ruin your look and it can actually make your hair harder to style. Start with as little as possible and add more as you go.
Pulling your hair back with any elastic - Ensure that its covered without any metal showing as one thats not (including an elastic band from your draw) will snag in your hair causing breakage and possibly even pulling hair out from the root.
Getting stuck in a style rut - Take a look at photos from 10 years ago and then look in the mirror, if your hair looks the same, your in need of a change. it doesnt mean that you have to make a major change either
Brushing your hair too much - The old advice about giving your hair one hundred stokes a night is not a recipe for healthy hair. It leaves hair more vunlnerable to breakage and brush wet hair is never a good idea. Though just a quick brush once or twice a hair is healthy for the scalp and using a wide tooth comb after you get out of the shower.
Ignoring the health of your scalp - If the folllicles aren't keep clean and healthy, then you won't produce healthy strong hair. Treating it well can simply include giving it a little extra massage everytime you wash your hair to stimulate it and making sure you wash off all residue as it could clog the follicles.
Pulling out your grey hairs - Pulling it out will make it grow back wiry and because it will be short, it will stick up straight. so your better off going for a rich colour hair dye to cover up the greys.