Just got back from the States and have a new tip... well it's a mix of half a tip from Hamish and half a tip from Todd Boman from Moksha Yoga Chicago. So, I've always had a big problem with this posture, especially going down and touching the floor and then coming back up. But I've got a great tip from the masters...and it's worked.
1) Take your ankles wider than your legs. I can't remember what this does, but Hamish says it works and it does! So there.
2) Press your thumbs into your inner ankles, I don't know what it does but Todd Boman says it keeps your shoulder girdle active so you can come back up!
So there you have it, try it, and let me know what you think :)