Homeless, this is the position that works well for me when seated:

The (acoustic) guitar's waist goes on my right thigh, and I put my right foot up on something. I find a hard shell case is the perfect height for a foot stand when seated on a normal kitchen chair. Putting right heel on chair/stool rungs is another option - if there's nothing available, I sit with my right foot on tiptoe. Having that right foot up really helps me to hold the guitar in a comfortable position, and prevents it from sliding along my thigh.

Marion