Put your hands on your upper backside, the reference to the hips is about your skeletal hips - you want your hands on your butt. Keep your thumbs with the rest of your hands pointing down to the floor and bring your elbows right back behind you. Keep the tops of your feet flat on the floor and your shins flat on the floor. 

Don't fling yourself back. Take your time, move in unison with the rest of the class. Elongate your spine, push your hips forward first and then relax your head. Don't 'drop' it back. Ouch. Relax it back. Now pause. Lift your chest up and push your hips again. You want your hips to stay forward the whole time. Keep your tailbone long. 

Reach back and grab your heels (or just keep holding your backside). Did I mention to make sure you don't sacrifice the hips? They don't come back. Keep lifting your chest up to the ceiling. Relax your neck. Keep breathing gently in and out through your nose. Draw your shoulders towards each other. 

Exiting postures correctly and calmly is as important as entry. Come out of camel  slowly and carefully. Hands to your hips one at a time. Look at yourself in the mirror and try not to slump down or do any exaggerated sighing or huffing and puffing. Carefully and mindfully turn around for savasana. 

Use the lines to place your knees six inches apart. Keep your knees and hips aligned over this line. Don't let your hips drop back.