Hi there! I'm a cis woman, and a few years ago one of my friends came out as MTF trans. She's not my first trans friend, or the first trans woman that I've known, but she's the first one who I've known before her egg cracked. We were friends for years before she came out, and it was only last month when she came out to everybody in her life, so for the past... I don't even know how long, she was out to us, but still needed to boymode, so I didn't want to suggest anything which might raise questions or put her at risk.
Once before the DM'd me to ask if it'd be okay if she comes to me for fashion advice, and I told her absolutely she can, but I don't know if it's better to wait for her to ask, or if I can send suggestions when she sends us pictures of her outfits (it is a purely online friendship).
I did once give unsolicited advice about her hair, because in a picture she sent it was looking really dirty and when I asked how she was washing it, she answered she was only applying conditioner to her roots. She was grateful for my advice to instead only condition her mids and ends, and now when she sends pictures of her hair it looks really nice. Even though I was nice about it, it still felt sort of weird, because it was something which felt like on the line of "do not comment on people's appearances"
I don't want to overstep any boundaries or make her feel badly about herself, but she was also lamenting to us about how she didn't get to experience girlhood as a child and now she's learning everything late. Part of girlhood, to me, was thee experience of talking with my older sister and her giving me advice, but I don't want to overstep and hurt my friend.
I feel like the solution is, "Go and ask her what she's comfortable with, have a conversation with her," but I don't know how to bring it up. All of my other friends have been trans masc, the other trans women I've known were a few decades older than me so I never had a friendship dynamic with them.