Many, many stores offer personal shoppers for free now.
Even JCrew and Banana do this! You make an appt and its totally free. Try it out
They often tell you about sales in advance and hook you up with coupons too.
Over time I have developed my own sense of style. Having for so many years just bought whatever I could button/zip up and didnt look atrocious, a whole new world opened up when lots of things could be zipped up. Hehe
Dont be afraind to try anything on, take pics of yourself, and then return later after you have had time to think it over. And when things truly fit, dont be afraid to buy many of them (if you are staying one size!).
My #1 rule is about fit over style. Not long ago everyone had their clothes tailor made just for them. The invention of ready to wear is horrendous in my opinion. Hardly anything truly fits anyone, regardless of how small or large they are. My biggest tips are around making sure your shoulders fit, your waist and butt dont pinch or gape, you can sit without baring your *** and that overall you create a nice lean line. This is one area where looking at models helps, look specifically at the fit. And always always always sit down, bend over, walk, etc to test that out while trying on clothes.