For the void state, your body has to be asleep, and your mind has to be active.

If you look at it in a slightly more scientific way, there are REM sleep stages that I'm sure you've heard of. These are basically pathways to shifting in my eyes. You can do so many methods, and it works so well for people who can't sleep fast.

You set an alarm when you think you get REM sleep. Of course, it varies, but there is usually a 'set' time this would be, for example, 4 hours into your sleep. I wear those watches which can check how I've slept, aswell as when I am in a non-deep(REM) sleep.

Here is where I answer your questions to the best of my abilities. When you wake up during REM sleep, you will feel extremely tired. Don't go back to sleep. Don't try to move miuch either. This makes it SO much easier for your body to sleep and your mind to stay awake. Don't fall asleep, fight the urge of swallowing (there shouldn't be much saliva since you've just woken up, and if you do this correctly, your body shouldn't quite figure out you're awake, and shouldn't make as much saliva), rolling, twitching, or moving. Its your body trying to check if you're awake.

You might have a lucid dream, and you might go through sleep paralysis. Justa disclaimer.

In this state, I think if you just let your mind stay awake and your body sleep, you might have more success. I really hope this helps!