Loudspeakers are significantly affected by both location within a room and the surroundings. It is only possible therefore to offer general advice. Please use this as a basis for experimentation. What sounds right to you is right. Listen in particular for the depth and stability of stereo images and the precision of bass lines and seamless integration of the sound. If your amplifier is fitted with tone controls bypass them or set them flat before adjusting the position of the speaker in the room
Firstly, follow the recommendations for stand height for
stand mounting loudspeakers. Floor standing models will
get the tweeter up to the right height by their design. The
tweeter should be in your sight line.