Here's a simple method of employing a basic M16 combat sling to yield added support in the offhand/kneeling positions, and significant downward/rearward pressure with the bipod in sitting or prone. This can help reduce bipod hop with some of the lighter rifles, and aid in self spotting.
Basic setup is a simple loop forward using the slider to adjust loop to best length to fit you. one setting works for me in all positions.
Usage is simply inserting the forward arm through the large loop to your upper arm, then using your upper arm to apply or maintain tension, as needed. No tightening of the loop is necessary, it's real easy/fast to get in/out of it.
Offhand:
Kneeling:
Sitting/bipod (Harris 12-25" swivel, fully extended):
Prone/bipod (Harris 12-25" swivel, fully retracted):
Basic setup is a simple loop forward using the slider to adjust loop to best length to fit you. one setting works for me in all positions.

Usage is simply inserting the forward arm through the large loop to your upper arm, then using your upper arm to apply or maintain tension, as needed. No tightening of the loop is necessary, it's real easy/fast to get in/out of it.
Offhand:

Kneeling:

Sitting/bipod (Harris 12-25" swivel, fully extended):

Prone/bipod (Harris 12-25" swivel, fully retracted):
