Martial arts classes can be a hard thing to walk into. You have a whole lot of people, dressed the same, who all know each other and seem to all be experts, when you walk in they all look at you as if to say 'yeah what?' Now, a good class will be friendly and welcome a new person especially a beginner but often those who have trained for a while forget what it's like to be new and know nothing, they want to get on with the class and can't really be bothered with showing someone the ropes.
A few years ago, I fancied doing some training with a JKD group that trained in the local sports centre, I phoned the instructor, he said great, you're welcome, just come along. I turned up, didn't wear a belt, just white t shirt and black gi bottoms ( I'd asked the instructor if that was acceptable), the men of the class, no women in it, just looked at me, they weren't hostile, just uncomfortable. One of them asked if I was lost thinking I was supposed to be in the gym part or a gym class. If I hadn't been as confident as I am I would have walked out, it was like a wall of blankness. Not unwelcome but not welcome either. When I said I'd come to train, they were at great pains to point out they trained 'hard' and I might get hurt.
Anyway, quick warm up and we got started, pad work to start with, everyone in a circle with gloves on, one in the middle with pads, going around the circle so each could punch the pads. Now without knowing what I could do each one punched those pads as hard as they could when I was holding them. They didn't ask if I was a beginner, experienced or even knew hold to hold the pads. If I'd been a beginner would I have had the confidence to ask any of them or even the instructor what to do, in my experience beginners don't tend to ask on their first class, they are usually quite shy and wait to be asked or told anything. The punching wasn't as much hostile as done in the spirit of discouragement only I guess to their disappointment I'm not fazed, I hold pads for pro fighters so wasn't bothers and when it was my turn to punch, used good techniques to punch the pads harder than they could. No one was wearing belts, I found out that was because no one had graded yet...the class was only months old. I don't know to this day whether the instructor was having a laugh or not, I went for a few more weeks, got to know the guys, they were earnest in their training but the instructor left and the class closed down.
This wasn't a specific male attitude, it was the attitude you get when people have been in a club/class/group for a while ( but not long enough to have the 'show off' bit wear off) and want to show they know more than the 'newbie'. I've seen in in fitness classes as well from men and women, though the one class I went to was circuit training, one bit was a long punch bag on the floor which you had to punch, knee etc, MMA style. Of course that was easy and I got stuck in like an MMA coach lol. I didn't realise it had gone quiet and they were all watching me, I stood up grinned and shrugged then moved on to a kick bag.
Women aren't so bothered about changing rooms, a clean toilet is nice preferably not shared with men who pee on the floor but as long as it's clean it's fine. The starting and finishing time of the class is important, even today most childcare is done by the mothers so it has to fit in with children's bedtimes and family meals, a lot of women do shift work because it fits in with their others halves work schedule. A lot of women also do part time work in the evenings. Also it depends on how much the classes coast, it's hard to justify spending money that could be used on children or housekeeping.
Female instructors are good because they see things from a female point of view which with the best will in the world men don't especially when it comes to self defence. Also white Gi bottoms are a pain in the ****, women don't like wearing white, go for black.
If the posters seem to be angled more to men than women it will put women off, the place you train at may also be overly geared towards men. We have leisure centres here, which hold gyms class, spinning, yoga, 'bums, tums and legs' classes etc so there are a lot of women attending those classes as well as using the gym itself, so posters there work well. It's even better if they can see a class going on, hold an open evening, advertise in in local newspapers. Do demos at local events, like school fetes ( I don't know if you have them but you know the sort of thing), give out flyers to mothers at school gates, put posters up on libraries. Have an open mat where you invite martial artists to come and roll on the mats, often they are done for charity here, held in local school/college/uni etc gyms, raises money for a local charity, gets you publicity ( inform your local press how much you made and who for, sometimes local radio/television will send someone along if you let them know beforehand) and non martial artists can see you having fun, being friendly and likely there will be a few women there. Often people bring non martial arts friends to come and watch which they don't get to on normal classes, so that will get your classes talked about and you never know a new student or two.