Phil's Rambling Rants
I use one, though not as often as I should.
I vary the amount of salt based on whether I have symptoms or not. If I need to kill an infection, I use more salt. Otherwise, I use about a teaspoon or so.
I tend to make the water warmer than room temperature, as I find that it penetrates the fluids better. Though, the day I forgot to turn on the cold water at all and just use hot straight out of the tap was a day I will never forget. Burned sinuses are most uncomfortable.
I've never used anything other than salt, though I had a friend that put peroxide in his. I've not been so brave.
So far as getting it deeper in, I know some folks that use a pressurized system to do that. For me, I've found that experience shows you how to move your head to get it deeper. It's probably not as deep as the pressure system, but then you're just looking for improved health, not to become a bionic man.