If you are entering, or re-entering, the world of style (as opposed to just being concerned with looking decent in public), the choices can be overwhelming to say nothing of the inherent fear of feeling like an idiot if you spend your hard-earned dollars on the wrong things. It just seems easier to keep wearing what is familiar.
Purging is also dicey because, again, outside the obvious "I know shoulder pads are dated" mantras, the details that date or make an item current can be pretty subtle--as evidenced by the host of "is this dated" threads on YLF and the lack of uniformity in the responses. Tricky, even before you see an expensive jacket in a trendy boutique that CLEARLY has a padded shoulder. And only keeping things that fit your current, or aspirational, style means nothing unless jeans, boots, a T-shirt, and the nearest jacket in fact constitute a "style"--which means you are probably just fine and can relax and go do something else.
If any of the above strikes a chord, I'd say you have probably found the right spot by landing on the YLF site. Pick any one of the stylish ladies you admire here and dig back in their posts three or four years--and prepare to be astounded at the transformation. But it didn't happen overnight.
All the advice that you've been offered is good, but, if you are wondering how to get started, l think unfrumped has given a good entry point. Find an ensemble in one of Angie's posts that appeals to you and try to replicate it at a pricepoint that seems reasonable using the Finds feature as a shopping guide. Wear the outfit and see how you feel about that "look". Then maybe try another outfit or two, this time incorporating some of the clothes in your closet that you like. Once you start wearing clothes that make you feel fabulous, then start purging because now you have a benchmark for evaluating the rest of your wardrobe.
When you do start purging, aim for a very small wardrobe of pieces that will fulfill your daily needs--AND which make you FEEL great. Go with how you feel in something instead of concentrating on how you look. If an outfit makes you FEEL confident and gorgeous, you have a winner.