Good basic form on Romanian Deadlift (RDL).

The key to this exercise is to not JUST kick your legs out, but to lean back with your torso simultaneously.  These can also be done to each side; for this you simply rotate your legs and hips and kick them out, then switch to get the other side. 

Lay in the supine position with your hands clasped behind your head, head up off the floor, and one foot held straight out six inches off the ground.  The other foot is up also, bent so that your foot is placed on the straight leg's knee.  All crunches will be performed from this position.  When the set is complete, switch sides without putting your feet down.

Roman Candles can be done while on a bench [shown] or on the floor, which is more common.  To do this exercise, lay in the supine position and either place your hands beneath your hips [if on the floor] or gripping the bench.  Now, keeping your legs straight, lift them up into the air and, using your abdominals, hoist your hips into the air also.  Do not rock into the exercise, squeeze your abs for every rep.

This exercise is done from a sitting position with the feet slightly off the floor. They can be crossed or uncrossed [uncrossed is harder]. You will also lean back slightly to give your body a sort of "V" shape between your torso to your knees.  Now just twist so your hands can touch the floor on either side of you. 

Keep the legs straight and touch the contralateral [opposite] elbow to the leg.

*This exercise is typically done by the 4-count.  [This means: say you start off with the left foot--raising it will be "1".  Then, when you replace it with the right, that's "2".  Left again = "3", then right foot = "4".  Each set of 4 equals one repetition.  Example count-off: "one-two-three-ONE, one-two-three-TWO, one-two-three-FOUR" and so forth.

Hang from a pullup bar.  Bring your knees up to your chest, then you will curl your butt into the air, making your knees come up more to your face-level.  It is important that you do this!  Most people do only the first part, which primarily targets the hip flexors.  Another variation is to just bring your knees up to face-level without the hip curl.

For this exercise, you will assume the supine position with your hands placed beneath your hips for support [to increase the difficulty, you can either place them out at your sides or behind the head], feet 6 inches off the ground, legs straight, head up off the ground.  You will then "flutter" your feet, keeping your legs straight at all times.  Proper form also calls for pointing of the toes.

Use an Olympic barbell and plate like so.  Keep your arms straight throughout the exercise and your back straight.  Focus on using your core to do the work.

For this exercise, you want to keep your torso straight, head in line, arms extended straight.  Your legs will be together and straight also.  A progression to this would be to incorporate a MBall [medicine ball] into the exercise.