Once you become fashionably aware, one of the biggest worries I think people have is how they are going to "re-invent" their style throughout the years. Now there is nothing wrong with re-inventing your style, and I'd say when you're young(er), go for it, you have nothing to loose. However I like the idea of making age appropriate style upgrades because there comes a time in your life when you have to stop wearing one thing and move on to something, well.... age appropriate.
My best advice when it comes to personal style is becoming fashionably predictable, which really means that people will come to expect what you'll wear on a daily basis. You could say this is boring, but really if you have established a personal style, your daily routine will probably already be unique, which is the whole idea of having style in the first place.
I've been abiding to this fashion code for a while now. Once summer hits, I'll have shorts or pants on with a Linen guayabera, sandals during the day, I'll toss on some loafers at night to dress it up, and I'll go sockless with all my shoes while the warm months persist. The rest of the year, I go solid bright colored socks in winter, 98% of the time I will have a collared shirt on, and if it's tucked in I will more than likely have on a tie. A day off for me is to go un-tucked and no tie. My personal style can get even more routine with the gray scarf I've had for over 6 years that I wear all winter, the two ways I wear my hair, and the same cologne I've been wearing since I was 14.
Now the ladies do have a few more options for accessories and hair, but at the end of the day the same rules can apply to a woman's style. If you wear heels, dresses, and skirts five days a week, on your day off you can pull out your favorite jeans you've had for 4 years, and you're already sticking to the rule of predictability.
The point is that I'm very predictable on what I'll wear each day, and that's ok! To be honest it makes things easy and my personal style very well established.