The first rule of thumb for me on public land is and always has been, if there is a truck (or car) parked where I had planned to go in, I go somewhere else.
You don't know if there is one or four people in that same spot that all rode in together.
Now, if I happen upon another hunter (it happens) I make eye contact and let them know that I am aware that they are there, and back out as quietly and quickly as possible so I don't spoil their hunt.
I have had another hunter come in where I was hunting, and I try and get his attention and let him know that I am there. I can't whistle to save my life, so I will wave my orange hat and that usually does the trick. Most of the time they acknowledge me and move out...sometimes they don't and I will leave, but not quietly. T try to be as respectful to other hunters as I want them to be to me.
