I don't care about looking older. I am getting older - it's fine, I'm happy about it and there are many many positives from it.
There is a fair amount of casual ageism and sexism on this thread, and in some cases, bitchiness and snide-iness, which really isn't necessary or in fact sisterly. We can exchange tips or advice in a positive way - but actually wear what you want, accept you could actually (shock horror) look your age, and, dress for yourself.
Since when you do you read about men being accused of looking their age, or (god forbid) looking frumpy! Frumpy is a word reserved for women. And, on this thread, being used by women. We can only change things if we change our mindset as well. How can we expect men to stop all this stuff if we don't stop it ourselves.
Rant over.
That said, I think (and I am very interested) in looking my best. And for me that's about wearing what makes you feel good. Because if you feel good, you look better. By this age the advantage we have is that we know what suits us. We know what season we are (because we're cliches) - so I won't wear orange or brown now because i know not to. We also have confidence of not caring what people think. It's great.
I love buying clothes, I do make mistakes sometimes, but mostly if I stick to wearing what suits me and what makes me feel good, I do ok. I get compliments mostly from women (and that's not a stealth boast honest) which mean more to me than the menz anyway and I dress for myself.
So I do wear short skirts -because they suit me, and I don't buy into the whole sexist mutton-dressed-as-lamb thing. I don't wear them with sheet tights or high heels, but I wouldn't in my 20s either. I don't wear maxi dresses because they look like tents on me (and in fact most people who wear them imo) and I have long hair because I like it. (I made the mistake of having a bob once...). But I think it's a case of finding what suits you and wearing it and being confident. so Op, take the advice of your mum by all means, but ignore the age-ist claptrap.