At home, in your back yard, gently lay the bike down on its side. Now you get to practice picking it up!
Try several of the techniques you've read about. Dead lift, butt to the bike seat, etc. Learn which ones seem to work well with you and this bike, and which ones don't. I will agree that the butt to the seat technique really only works with dressers that only fall over partially. I've often found that some sort of dead lift, gripping the lower handle bar in one hand and the seat in the other and levering the bike often works well enough for me.
I'm also not at all afraid to use chunks of wood, dead limbs and rocks. Get the bike partially up, or even one end partially up, and shove something under it. Repeat on the other end and as necessary. This can become more important as the day wears on and I'm getting more and more tired.
I've also learned positioning the bike is darn important. Nothing brings tears like getting the bike up...and over, falling onto the other side. Or getting it up and then trying to chase it down the hill as it starts rolling away. I will drag whichever end moves more easily in order to position the bike in a way that not only can I get it up, but can do something with it once it is upright. Being upright and facing down a ravine is not good for example.
A neat piece of kit that I've lost apparently is a deer hunting block and tackle. A little too big to fit in a pocket. But it is able to lift several hundred pounds, and with its hooks and excess rope, you can connect it to trees and such, to drag a bike around, and to help lift it upright. If I can't find my old one, I'll go buy a replacement to carry on trail rides.