Ideally you’ll want to use a high chair. If all you have is a regular height chair, you can place a firm cushion or enough pillows on the seat to make sure that your right knee is below the level of your right hip.
Your right thigh must slant downward so that your knee is below the level of your hip:
Do not lean forward while sitting:
Do not sit on any low, soft surfaces such as a couch – this would break the precaution of bending your right hip more than 90 degrees:
Keep your knees apart.
Do not cross your legs:
Don’t rotate your right leg in, as you might while reaching for phone while sitting: