For Western jeans (probably with chaps) would ok, but seamless jeans or special riding jeans you get at your western riding shop would be better. I’m not that much into Western, I was trained English. A Western rider might give better advice.

For English you *need* special riding pants with leather pads on your knees or even better from under your knees up to your butt, this greately helps your posture.
I’d opt for something like this: http://www.tackinthebox.com/Products/Rider/cl304.htm

Also, you need a helmet for security and I’d advise you to get a pair of gloves or the reins will excoriate your skin between your fingers. And this *hurts*.

I wouldn’t buy boots yet because a good boot (and do NOT buy plastic or gummy, go for leather because otherwise you will either freeze or sweat and you won’t be able to keep proper posture because the material will be slipping around on the saddle, leather will make it easer to you to keep seated properly) because they’re really expensive. I’d go for a good shoe and small chaps instead (shoe like this: http://www.tackinthebox.com/clothes/Sweaters_etc/cl_00thumbnails_clothing3.htm ). You need something with a little bit of a heel so you won’t be caught in the stirrups if you fall.
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