Whoo, I love yama's mum!!
Mine was shite at most things, and great at some too. One important factor was that she answered questions about sex & stuff accurately and age-appropriately. I fell around in hysterics when I found out my school friends thought they'd come from under bushes/in a bird's beak! (Naturally, they thought I was lying - which put our teacher in an interesting position ) You can get really helpful books for all that now.
Once I passed puberty, she started answering my questions in a more emotional way, with 'moral' overtones, which was extremely unhelpful.
She bought me a pack of mini Lil-Lets, read through the leaflet with me and advised me to take my time, it's worth getting the hang of it
She forgot to tell me about pubic hairs and made an absolutely awful comment when I told her I'd started growing them & thought I was turning into a man!
She took me to buy a bra way too early. It fitted wrong and made me look stupid. A school friend's mum phoned her with better advice, after which we went to get a proper teen bra
She battled my dad to let me go out in a fashionable dress - I was v.v.grateful for that!
She bought me my first moisturiser at 13. It got me into a habit that has paid off, over the decades.
Most helpful of all, perhaps: my parents got me subscriptions to girls' magazines. I started out with Bunty & Judy comics (anyone else remember those?) then moved on to teenage mags, which should never be underestimated as a source of wisdom on all things girlish
Have fun!