I've been doing the same this year. With a new job, extra income and grown children I've finally had the headspace to sort myself out a bit. I've also found Youtube helpful for finding women of a similar age who discuss clothes, make up, hair etc.
It's taken a while to get to grips with it but I'm starting to have a clearer idea of how I'd like to look. A few things I've discovered so far that have helped -
A good hair cut, decent shampoo/conditioner and products for blow drying. I'm using Pureology S&C but a lot of people like Kerastase, Olaplex, Ouai etc. It's expensive but it's made a difference and I've found I don't have to use as much of it as supermarket S&C. I'm peri menopausal and I've found my hair has changed recently so my Aussie products I've used for years stopped being good enough.
Accessories - I'm making a concerted effort to wear jewellery most of the time. Just simple chains, a bracelet and some nice hoops. I used to wear silver jewellery mostly when I was young but something has changed and I look a lot better in gold. Whatever clothes I'm wearing I look a lot more together if I add a few nice bits of jewellery, a nice scarf or belt. Doesn't have to be expensive, I've bought some nice bits from the high street and Etsy for £10-30.
A good coat that is flattering and fits properly. This is something, especially for winter, it's worth spending a good amount on to get something classic and quality that can be dressed up and down and will last a few years.
Two nice useable handbags - similar reasons as coat. One black and one brown/burgundy/taupe or other neutral-ish colour.
Shoes/trainers/boots - admittedly this is one I'm still getting to grips with because for some reason I've never enjoyed buying footwear. I don't think you need loads but you do need a range of footwear that compliment outfits easily and wear well. It's annoying when you put a nice thought out look together then realise you own no footwear that works with it. This happens to me a lot.
Make up and skincare. I came out of the child rearing bubble to realise all the make up I had (not much) was at least 10 years old and I only knew how to apply make up one way - which was the way I did it when I was 20. Not going to cut it at 48 so I've had to re-learn. Ditto how to get the best out of my dry, rosacea prone, mature skin with skin products.
This is the area Youtube has been most useful for. Ignore videos from anyone under about 35, yes they look great but you can't replicate the style of people who have young firm skin. Less is more - it's not really about looking made up (unless this is what you like) but not looking tired, sallow, blotchy and all the other menopause delights. I feel mentally better if I catch sight of myself and I'm not all eye bags and hormonal breakouts.
Perfume - go smell loads. Buy one you really love even if it's £££ and have a signature scent (or two if you want a summer one and winter one). Use it everyday. No saving for best!
Lastly and this should be really obvious but it wasn't to me for ages. Shopping! You have to physically go shopping, discover what shops and styles are out there. Look and touch clothes, try stuff on. Take a friend who will be honest about what looks good. Only buy clothes online once you know a brand very well and have a good sense of what suits you. All the best things I've bought recently I've tried on first.
Don't impulse buy but just figure out what you like because if you're anything like me you won't know any more because you've spent a chunk of years mostly buying leggings from Asda and the odd panic bought item from Next on the rare occasion you were invited somewhere. Items you never loved, never really suited you but they 'did'. This takes a while and I've not fully got there yet, partly because I'm attempting to lose my excess weight and being even a couple of stone lighter will make clothes buying easier.
I'm not going to pretend all this comes cheap. I've probably spent about 10 years of budget in one year however I've looked at it as just recouping what I owe myself for the 10 -15 years or so I've spent not very much on me. If I never see a pair of supermarket leggings again it will be too soon!