The absolute main thing is that the woman is kept entirely informed during labour. It's good to be armed with information beforehand but I think for a lot of people it can be a bit overwhelming and you won't necessarily remember all of it when the time comes. Every main possibility should at least be mentioned in antenatal classes so it's not a complete bolt out of the blue if someone mentions an episiotomy for example. In the delivery room is the not the first time a woman should hear a word like that.
What annoyed me in labour was that the older midwife who came in after a couple of hours very much had the attitude that this was her show and I just had to go along with what she wanted. That was in complete contrast to the younger midwife I'd had up to that point, who just let me get on with it and listened to what I was saying. The older MW came in bleating about ventouse and episiotomy without ever once explaining why she was considering them. That sort of treatment is what contributes to a woman feeling out of control - the feeling that everyone else seems to be in on some secret that you're not aware of. In fact, I think it's just that some older midwives (not all of course) come from the era where what nurses and doctors said was law, and the idea that you work with a patient and actually listen to them isn't even on their radar.
When I asked three times why she wanted to use a ventouse she finally admitted it was because their monitor was faulty and they couldn't get a stable trace of DS's heartbeat. Given there was meconium in my waters they were understandably concerned but I didn't feel faulty equipment was a good enough reason to start intervening and I flat refused to consider ventouse. She then went on about wanting to do an episiotomy again due to lack of a stable trace. Note that there was no actual evidence of DS being in distress (beyond the meconium), she was just insisting on these interventions because it would make life easier for her as she wouldn't have to ask the other MW to hold the trace to my belly. I again refused that, but was forced to give in to her insisting I go on a bed (having laboured on my feet/knees up to that point) because I was so tired I couldn't argue any more. If she had just bloody well left me alone I could have had DS out in half the time, I'm sure of it!
The younger midwife subtly praised me afterwards for standing up to the older MW and criticised her decisions in a very roundabout way. I appreciated that as I was worried I had been foolish in not listening to her. DS was totally fine by the way - needed a little suctioning when he came out due to the meconium but that was it.
So what I would advise is that you let women know that they are in control in labour and that they should expect and demand that they are kept fully informed of what's going on at all times. I doubt you will tell women that though, because it seems easier to patronise them or as in my case, pretend their baby is in grave danger, in order to get them to do what the MW wants.
BTW I am having a homebirth this time round because I believe the dynamics will be very different in my own home. I'll be in my own space and so won't be so easily bullied and I'm hoping the MWs will have a bit more respect.