Oh I know how expensive this sport can be! Start out smart and don't let any man out there say their shoes or clothes will fit you. I have 4 bikes, and I wouldn't buy a bike today without disc brakes, be they hydraulics or mechanical. Two of my bikes are full suspension, two are hardtails and I love them all. It depends on what I'm riding that day. When you get your Specialized, make sure you are fitted by the bike shop. They should be able to swap out your stem if its too long and adjust your saddle forward or backwards so the fit is just right among other things. Your saddle angle will be a big deal, so play with that. Switchback climbing is better dealt with a shorter stem (you'll be able to climb easier). I don't know what your head angle is on your bike, but going downhill, sit back on the saddle, stretch your arms forward like you are sledding, it will be much harder to endo that way (fly over the handlebars). The steeper the decline, the more you want to sit back on that saddle, sometimes I am over the back wheel and not even on the saddle. Like Christine said, start out with clips, forget the flat pedals. I'm not a fan at all on cages, they are more dangerous (to me) then clips as your front foot can be trapped in. I would go for mountainbike shoes with spd clips and a basic Shimano set-up. There are lots of places on line to buy, you could get shoes for $50 and pedals for the same price. Be careful about the fit of the shoe to begin with. You want a snug heel so you can break out of the pedal when you need to. If your heel slips when you walk in them, they aren't right for you. I would really suggest looking at Shimano, Diadora and Sidi as they have a great women's line. I'm not sure about the trails out there, if they are muddy, but my favorite pedal is the Shimano 969, I have four sets and they are bomb-proof. Buy them once and your are done with it. They release very nice and you won't get stuck in your pedals because they have a beautiful adjustment. You'll struggle hard to keep your feet on pedals and the first time over a log you'll be flopping all over the place. With clips, you become one with the bike, climbing will be so much easier and I know it will be a little intimidating at first, but it will all *click* after a few rides. You'll crash every now and then, but it's not going to stop you, promise!
Get yourself a good pair of shorts, like Sugoi, Pearl Izumi, Primal. A few jerseys with a zip back pocket, a couple of sports bras. You need a camelbak with a bunji cord on the back. Not to mention you will never ride without a helmet...right?!! I would suggest full-finger gloves if its not too hot, your grip will be more secure on your bars, especially if you sweat. Socks are also something that will make your day, and bike socks are the most fun socks! In other words, you want to be comfortable. Somewhere down the line you'll add a jacket and longer shorts or riding pants.
I know the start-up is daunting, but it settles down after a while, and then its just maintenance issues on the bikes. I can't stress enough about keeping your chain clean, it will keep your drive-train in such good shape. Pay attention to your tires. If the trail is very hard, underinflate them some for better grip. You'll find that these little things make a difference.
Also, don't try and keep up with your husband, if it makes you uncomfortable. Go at your own pace, keep your eyes scanning 4 to 6 feet ahead of your wheel and relax. Momentum is definitely your friend, go too slow over a log or rock and you will naturally come to a stop. Get off the saddle slightly and roll over stuff, and hang on to those grips. Brake with your rear brake first, not the front brake or you'll have the dreaded over the bars event. Sometimes it helps to *brake* and steer at the same time when you come to tricky spots and you want more control. If I'm navigating a switchback that is particularly sharp, braking in the corner helps me out every time.
What ever you do, don't let anyone push you to go faster or do what you don't want to do. Everybody has a learning curve and suddenly it will all make sense. If you have any questions about bike parts, just send me a pm. Below are two places to really learn about biking. Mtbr.com has a woman's forum, which is the first link below. You'll have every question answered there. The second link is a list of all the bike associations in California. The rest are sites to shop from, which have good prices and sales from time to time. Personally, I do the bulk of my bike shopping on line, the prices are better unless you have a great bike shop you go to. Hands down, the best women's shopping is at TeamEstrogen.com, they have great customer service. You will love this and its the best form of copious fat burning fun in the world!
http://forums.mtbr.com/forumdisplay.php?f=94
http://mtb.live555.com/mtb-norcal.html
http://www.teamestrogen.com/?utm_source=teamestrogen.com&utm_medium=urlbar&utm_campaign=dns
http://www.performancebike.com/index.cfm
http://www.jensonusa.com/?sc=ggl&x=y
http://www.sierratradingpost.com/d/4287_Cycling-Gear.html?cm_re=Control-_-Merch-_-OCyclingGear
rei.com
http://www.sidiusa.com/mtb.html
) or clipless shoes? You have to have something to hold your feet on to the pedals. Second - think about where you are on the saddle as you ride. If you are going up a steep hill, you'll want to be forward on the saddle - basically sitting on the nose (keep your butt down on the bike as it will give you more traction and keep the front tire from coming up). If you are going down hill, sit as far back as possible (some cyclists even end up with their abs on the seat and butt hanging off they push so far back) to keep the back tire on the ground. Third - speed is your friend. It's much easier to go over obstacles quickly than to try to go over them slowly. Fourth - know you will fall. I classify mountain bikers as going through 5 stages:
