Not sure if there is a preferred position, but I have a few positions I use –
Sitting at desk with the Venus attached by tied rubber bands to the desk.
As above but kneeling in front of the desk instead of sitting.
Laying on my side on the bed.
Laying on my back with the Venus suspended by a camera tripod.
Ohioman – I have a few Venus “demo” vids on Xtube if you are interested, search for ian_mason16