Not sure what's so hard about it.. lift from the hips.. if you drill the take off positions enough, you should have plenty of time to get your hands in and control take off, rotation, and potentially landing if you're really fast.
Just remember, once they leave the ground their direction and rotation are pretty much set. Help the lift, save the landing.
Personally, I don't spot fronts much myself. Unless they are dangerously low, they don't typically need it. If they are dangerously low, they skipped a progression step. Go back and fix that, not your spotting.
I also agree with the above poster - if you never fall, it's that much more shocking and scary when it happens in a meet, and causes so much more issues later on.
Some bumps and bruises are normal, in my opinion.
Edit:
I hope I didn't come off as too harsh. After re-reading it, I thought to myself "I just went to a more experienced coach to learn how to spot doubles.." And.. well, he kinda did say "what's so hard about it?"
But more importantly, he gave me a great tip - be pro-active, not re-active. Put yourself on the side of the gymnast, not in front or behind. Follow their center of gravity, and control the situation.
Hope that helps.
Good luck,
Ryan