Stronger, Flexible Quads?

I personally woiuldn't bother with the resistance machines uness you're already at the gym - just do squats. Lots and lots of squats. Once you progress and "air" squats are too easy, you can add a couple of dumbells or a barbell. Leg presses are comparitively easy (too easy), and don't work all the same muscles in the same way. Make sure you get low - most people barely make it down to parallel. I squat to a dynamax ball (maybe 14" tall?) - but you could use a box or just squat all the way down (see videos below).

Great tutorials: http://www.stumptuous.com/lurn-to-squat-good-e-zy

Editing to add - this is my general approach to every exercise that I stink at - I just do it more until I get better. Just like runners get faster by running, and pitchers get better by pitching, your squats will get easier by squatting! I do pullups, pushups, and squats (plus a lot more) everytime I go to the gym, and it's amazing how far I've come in 5 months.

When doing Hero's Pose stick a folded blanket between your heels and sit bones to alleviate any tightness.
The following poses are excellent for your quads.... Triangle, warrior one, warrior two and bound angle pose, The warrior poses really build a lot of strength in your quads.

I would hold longer on the warrior poses. How do you feel in child's pose? It gives a good stretch in the upper thighs as well.

I definitely recommend squats- use them as the base for all your leg training. Since they require the most energy, I'd advise to put them at the front of your leg workouts. I also would recommend using a box or bench to squat onto- this has been fantastic in helping me not only develop my quads, but also increase my overall strength in the squat. Just make sure to pause for a full second once you lower yourself onto the box. Plant your feet and use your quads to raise yourself off the box- your hamstrings and glutes will finish the movement at the top.

Other exercises you can try are the leg press, leg extension and lunges. On the leg press machine, position your feet near the bottom of the footboard (but not so low that your heels are not touching it)- this position will isolate the quads. Conversely, putting your feet higher on the footboard will isolate the hamstrings.

On the leg extension, make sure that your legs do not go past 90 degrees at the bottom and that they are straight at the top of the movement. This machine has a reputation for being bad on the knees, but that is due to either sloppy form and/or not taking the time to properly adjust the machine. However, when used properly, it's excellent for isolating the quads.

Lunges are also a great overall leg exercise- you can do these with your bodyweight, walking, standing, with dumbbells, a barbell or in a Smith Machine. A couple of general rules are to make sure your front leg makes a 90-degree angle both at the knee and at the ankle; and do not let your back knee touch the ground. It does take some time to get the form down, but it's well worth it.

A couple of corrections to the above recommendations: NEVER let your knees go past your toes or go below 90 degrees when you do a squat. This puts too much shearing force on the knees and can cause an injury. Same with lunges. This is also true of the leg press. When you do a leg press, bring the feet up high enough on the platform that your knees aren't past your toes when you are in the down or squat position. You want to strengthen your quads not risk a knee injury.

Actually, most all of the recent research disagrees in regards to squatting below parallel. More info in the links below:

http://www.t-nation.com/free_online_article/sports_body_training_performance/leg_training_myths_exposed

http://www.apec-s.com/Deep Squats.pdf

http://ajs.sagepub.com/content/22/6/768.abstract

I may be waaaaay behind you in fitness Yolanda - but when I was in physical therapy last Fall because of my knees, one of my major goals was strengthening the quads to support the knees. But because I had knee issues, things like the squats and lunges that others are recommending here were pretty much out of the question. If you want to start with a few things that will work the quads, but not stress the knees try:

1. (for flexibility) quad stretches - stand with feet hip distance apart. Bend one knee back so that foot is towards your bottom (touching if possible). Hold foot or ankle, keep hips in line. Hold for count of 5 full breaths. Change legs.

2. (for strength) straight leg raise - lying on back, tighten abs and slowly lift one leg straight up to about 45 degree angle. Lower slowly. Repeat for count of 10 and then switch legs. If you are keeping your core tight, you should feel this burn in your quads. If it is too easy, add ankle weights.

3. (for strength) Wall squat - standing with back against wall, slide down wall to squatting position with knees parallel to floor and hold, slide back up. Repeat 5 -10 times. The longer the hold, the bigger the burn. I do this with a stability ball behind my back, so I am actually rolling down the wall and it protects my back muscles during the move.