When my egg cracked and I came out to my partner, they went down a rabbit hole of YouTube videos and articles about how to be supportive and helpful. At one point, while they were bingeing all this stuff, they woke me up in the middle of the night, crying and apologizing for all the suffering and pain they read about these other trans people going through because they assumed I was having the same experience.

I sat them down and explained that not every trans experience is the same. I came out in the unique position of having a super supportive partner, utterly indifferent friends, and a work-from-home job. Realizing my gender and having the person I love be happy for me and supportive of me has been the most transformative experience of my life. Not because I'm painting my nails or shaving my legs, but because knowing myself, being allowed to like myself, and knowing that I'm loved and accepted for that has helped lift a 30+ year fog of depression and anxiety.

If you want to help your friends, just ask them what they need and do that. They should have a fair idea of what help they want.

the fact that you worry about that says you're already doing better than most people :)

my kneejerk reaction to people complaining about things is also to propose solutions, and i've only relatively recently realized that often people complain as a way of venting stress/other emotions, not as a request for ideas. i've found that bluntly asking if people are looking for support or just trying to vent works wonders, although YMMV if your friend group is less neurodivergent than mine. an offer of a hug is a good option too :)

wrt to your trans friends, honestly the best help you can give in most situations is just treating them as their preferred gender.