Here is a run-through of the exercises my horse and I started with as beginners and still do:
-Start with lunging, not to wear the horse out, but just until the inside ear is turned to you, stays there, and they are calm
-Then start from the front and work your way back with what I call cross-overs..in the front, walk into the horse's shoulder until it crosses its front legs, the side you're on should be the side that goes in front.on the back you should hold the lead rope by the horses eye and ask it to move its hind-end
-After that, I ask for some bending, I will reach the horse's nose to wear the girth should go..but it won't go all the way there at first, just keep working on it
-I always change what I do next..it varies from trot poles to some showmanship stuff to small crossrails to just brushing and tacking up
-After saddling, I will stratch out the legs by asking the horse to lift its front leg and stratching it forward, like this:
Thhat helps to make sure the girth isnt pinching them and I stretches their legs
-Next, I mount the horse
-After that, I ask for bending similar to what you did on the ground but in the saddle
-I do a lot of small tight circles all over, also TONS of figure 8's..you will drive yourself mad with figure 8's
-After you trust your horse to be sane, you cane do things like rollbacks..for these I use a senction of fence or a wall and run the horse towards it and do a tight, quick turn..be careful not to run our horse into it or go too fast at it, because some horses don't like being run at walls for some odd reason :P
Hope this helps..I've only been riding about 5 or 6 years, so I still consider myself pretty beginner as well
I like to start with large circles around a barrel (Or any other obstacle) and then decrease the distance before actually running the pattern. I like to lope up and stop before actually turning, so the horse knows that we aren't always going to be turning just because I run up to a barrel. I want him to know that I decide when we turn and when we don't.
I also suggest extended trots for distances. I like to extend for a few strides, collect a few strides.....and make sure you're posting when you want to go faster, and sitting when you're slowing down. But never let him break down to a walk.
And figure eight's are a must. I start by using the whole arena and the tighten it down before working my way out again.
Also practice stopping. Lots of backing up, but not enough to bore him. Keep your horse interested.....don't always stop in the same places, and maybe switch leads every now and then.
A little flexing never hurt either. Start by just standing still and bending the head until he gives, then while you're moving ask him to turn in a circle before moving out at a normal pace again. These small circles really helped me with Annie.
Make sure your horse always picks up the right lead. You tell him what lead needs to happen, and if he picks up the wrong one stop him immediatly and try again until he gets the right lead.
And remember when you're stopping, it's "Woah", Sit, Reins ^^
Western riding has very little difference then English. The horses should have all the basic work. They should give every part of their body to your legs and seat. They should stop and back. They should side pass and do shoulder in and out and they should be able to move their hip over at each gate. This is where you lead change comes from.
The only big difference is you sit the trot in western vs. posting the trot.
Once you can do all that they you will need to work on neck reining and working on a loose rein. This is where the work with your legs and seat comes from. You see horses moving off the reins. Most of that comes from the riders seat and legs not the reins. Once you have full control over the horses from the saddle the bit b/c just an accessory.