Merp, I am fortunate in a couple of ways. My hubby was into racing years ago and had a lot of advice to offer me. There are also lots of women in this region that ride and race so there’s almost always a women’s only class to enter somewhere. And there is a riding area near me that has a full-on MX track that I can go practice on any day. I would go and when it’s not busy, loop around one obstacle over and over again until I got more comfortable with it. I would also recommend any MX classes you can sign up for. The one I took really changed my mentality and upped my game.
It started slow for me. I did a race or two on my old trail bike, then realized I needed more suspension if I was going to really do this. Eventually got my 250 and practiced on it maybe a year before entering a real race.
Don’t worry about the other racers on the track, I believe the men’s beginners are riding to not crash and are willing to watch out for you. As I mentioned before, the teen boys are not always so careful. They are riding to win and don’t care if they land on you over a double.
Hang out at the track for a day and watch carefully the speeds that the different classes are moving. Do as many practice days as you can as well. Talk to people about starting out, most racers will be very encouraging and helpful. And don’t forget: Always hold your line. Now go!

Now a firm believer in neck braces! Don't look at the ruts; don't look at the ruts; don't look at the ruts...