The key is finding your own style. What suits you and you feel good in. Clothes that are well cut. What looks good on one person will look awful on another. This is where people often go wrong. They see clothes on someone they know, a model or mannequin and love the look, but it won’t necessarily suit them, due to shape, colouring, personality etc.
A good tip is find a person in the public eye who has a similar shape and colouring to you. Then look at what they wear and replicate that. Not necessarily exactly, but as a guide. They’ll likely have a stylist for some occasions, so you’re basically nicking the stylist’s advice for free!
I get basics from really cheap stores, e.g, Primark. Their cotton t-shirts (£4 ones rather than £2) keep their shape very well. I always wear skinny black jeans and they usually look good wherever you get them. I’ve tried more expensive places (when I had money) and it didn’t make much difference. Over half my stuff is second hand.
Also agree about ironing. I store stuff unironed. But press everything just before I wear it. T-shirts, jeans, the lot. Always inside out. I wash stuff inside out too and line dry. It stops it fading and is better for the fabric. Try to buy natural fabrics (cotton, linen, wool), as they always look and last better. Good undies are a must as they determine how things hang on you.
Finally, I don’t buy much and rarely get rid of clothes. I’m late 50s and still wearing stuff from my 20s. Not trousers as I’m not that skinny any more! Plus, occasionally wear my nan’s 1930s shoes and an early 80s new wave dress of my mum’s. Other than really faddy things, most stuff never goes ‘out of fashion’ (e.g. striped Breton tops, black and white dots, black leather jackets etc.)