say you're going 65 and you're cruising in 6th. You're exiting the highway you should(now this is exactly the way I do it. Everyone has their own style and this is mine)
1. kinda all at the same time. push the gas about 1/5 the way down to give it a little higher rpm for 5th to catch without jerking from being too high or too low WHILE pushing the clutch at the same time. Shift to 5th and come out of the clutch almost at the same time. It can be done very quickly
say 5th gets you down to 55 and you want to slow down casually
2. Push the gas about 2/5ths way down and floor the clutch.
Shift to 4th and come out of the clutch, maybe give it a little brake depending on how fast you're trying to slow down. Again, there should be no jerking.
3. Say you're down to 45 but you want to slow down quite a bit quicker. Push the gas a little over 1/2 way down to maybe 3/4 and push the clutch to the floor. Your rpms will be even higher and you will shift to 2nd and come out of the clutch RIGHT after.
4. Say you're at like 30 or so. Push the gas about 3/4 way down at the same time push the clutch all the way to the floor. Shift to 1st quickly and come out of the clutch and if you rev matched it good enough it will not jerk. Apply the brakes as necessary and when your rpms approach idle clutch in and put it in neutral.
That's kinda my way of doing it. After reading this and jumping in your car it will not go perfect for the first few tries so don't worry. I had a funny time doing it tonight. Once you get a feel for it you'll get good.
While trying to learn, you do not have to come out of the clutch quickly. Ease out but don't ease out too slowly. Easing out should take maybe 1 1/2 seconds but when you're good it happens like I said, kinda all at the same time.